197b5f9d1c
Loop relaxation logic in xtensa gas may produce code in which LEND register doesn't match actual zero overhead loop end. Fix relaxation code so that it produces a literal or a pair of const16 instructions with associated relocation record that works correctly in the presence of other relaxations. This fixes crash in X11 server caused by window movement. Loop relaxation has limited of 32K range, this fix removes this limitation. Fixes: http://autobuild.buildroot.net/results/e05522ce540f4ac23f9a3a8fec724694d9a23101/ Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
295 lines
10 KiB
Diff
295 lines
10 KiB
Diff
From 0dbdfb7918d0b0cfcb8883b24c1291574bf5bb7c Mon Sep 17 00:00:00 2001
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From: Max Filippov <jcmvbkbc@gmail.com>
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Date: Tue, 2 Apr 2019 14:32:42 -0700
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Subject: [PATCH] gas: use literals/const16 for xtensa loop relaxation
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Loop opcode relaxation that uses addi/addmi doesn't work well with other
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relaxations that may cause code movement. Instead of encoding fixed loop
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end offset in the relaxed sequence use l32r or a pair of const16 to load
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loop end address. This way the address of the loop end gets a relocation
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record and it gets updated appropriately.
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gas/
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2019-04-02 Max Filippov <jcmvbkbc@gmail.com>
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* config/tc-xtensa.c (convert_frag_immed): Drop
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convert_frag_immed_finish_loop invocation.
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(convert_frag_immed_finish_loop): Drop declaration and
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definition.
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* config/xtensa-relax.c (widen_spec_list): Replace loop
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widening that uses addi/addmi with widening that uses l32r
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and const16.
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Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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---
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gas/config/tc-xtensa.c | 120 ----------------------------------------------
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gas/config/xtensa-relax.c | 77 ++++++++++++++++++++---------
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2 files changed, 55 insertions(+), 142 deletions(-)
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diff --git a/gas/config/tc-xtensa.c b/gas/config/tc-xtensa.c
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index 3bdbbc931cfc..0cc06361cf6f 100644
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--- a/gas/config/tc-xtensa.c
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+++ b/gas/config/tc-xtensa.c
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@@ -10668,7 +10668,6 @@ convert_frag_fill_nop (fragS *fragP)
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static fixS *fix_new_exp_in_seg
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(segT, subsegT, fragS *, int, int, expressionS *, int,
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bfd_reloc_code_real_type);
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-static void convert_frag_immed_finish_loop (segT, fragS *, TInsn *);
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static void
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convert_frag_immed (segT segP,
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@@ -10910,9 +10909,6 @@ convert_frag_immed (segT segP,
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}
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}
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- if (expanded && xtensa_opcode_is_loop (isa, orig_tinsn.opcode) == 1)
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- convert_frag_immed_finish_loop (segP, fragP, &orig_tinsn);
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-
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if (expanded && is_direct_call_opcode (orig_tinsn.opcode))
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{
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/* Add an expansion note on the expanded instruction. */
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@@ -10949,122 +10945,6 @@ fix_new_exp_in_seg (segT new_seg,
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}
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-/* Relax a loop instruction so that it can span loop >256 bytes.
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-
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- loop as, .L1
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- .L0:
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- rsr as, LEND
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- wsr as, LBEG
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- addi as, as, lo8 (label-.L1)
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- addmi as, as, mid8 (label-.L1)
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- wsr as, LEND
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- isync
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- rsr as, LCOUNT
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- addi as, as, 1
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- .L1:
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- <<body>>
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- label:
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-*/
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-
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-static void
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-convert_frag_immed_finish_loop (segT segP, fragS *fragP, TInsn *tinsn)
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-{
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- TInsn loop_insn;
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- TInsn addi_insn;
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- TInsn addmi_insn;
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- unsigned long target;
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- static xtensa_insnbuf insnbuf = NULL;
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- unsigned int loop_length, loop_length_hi, loop_length_lo;
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- xtensa_isa isa = xtensa_default_isa;
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- addressT loop_offset;
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- addressT addi_offset = 9;
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- addressT addmi_offset = 12;
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- fragS *next_fragP;
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- int target_count;
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-
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- if (!insnbuf)
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- insnbuf = xtensa_insnbuf_alloc (isa);
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-
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- /* Get the loop offset. */
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- loop_offset = get_expanded_loop_offset (tinsn->opcode);
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-
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- /* Validate that there really is a LOOP at the loop_offset. Because
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- loops are not bundleable, we can assume that the instruction will be
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- in slot 0. */
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- tinsn_from_chars (&loop_insn, fragP->fr_opcode + loop_offset, 0);
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- tinsn_immed_from_frag (&loop_insn, fragP, 0);
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-
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- gas_assert (xtensa_opcode_is_loop (isa, loop_insn.opcode) == 1);
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- addi_offset += loop_offset;
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- addmi_offset += loop_offset;
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-
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- gas_assert (tinsn->ntok == 2);
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- if (tinsn->tok[1].X_op == O_constant)
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- target = tinsn->tok[1].X_add_number;
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- else if (tinsn->tok[1].X_op == O_symbol)
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- {
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- /* Find the fragment. */
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- symbolS *sym = tinsn->tok[1].X_add_symbol;
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- gas_assert (S_GET_SEGMENT (sym) == segP
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- || S_GET_SEGMENT (sym) == absolute_section);
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- target = (S_GET_VALUE (sym) + tinsn->tok[1].X_add_number);
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- }
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- else
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- {
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- as_bad (_("invalid expression evaluation type %d"), tinsn->tok[1].X_op);
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- target = 0;
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- }
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-
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- loop_length = target - (fragP->fr_address + fragP->fr_fix);
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- loop_length_hi = loop_length & ~0x0ff;
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- loop_length_lo = loop_length & 0x0ff;
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- if (loop_length_lo >= 128)
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- {
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- loop_length_lo -= 256;
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- loop_length_hi += 256;
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- }
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-
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- /* Because addmi sign-extends the immediate, 'loop_length_hi' can be at most
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- 32512. If the loop is larger than that, then we just fail. */
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- if (loop_length_hi > 32512)
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- as_bad_where (fragP->fr_file, fragP->fr_line,
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- _("loop too long for LOOP instruction"));
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-
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- tinsn_from_chars (&addi_insn, fragP->fr_opcode + addi_offset, 0);
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- gas_assert (addi_insn.opcode == xtensa_addi_opcode);
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-
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- tinsn_from_chars (&addmi_insn, fragP->fr_opcode + addmi_offset, 0);
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- gas_assert (addmi_insn.opcode == xtensa_addmi_opcode);
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-
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- set_expr_const (&addi_insn.tok[2], loop_length_lo);
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- tinsn_to_insnbuf (&addi_insn, insnbuf);
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-
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- fragP->tc_frag_data.is_insn = TRUE;
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- xtensa_insnbuf_to_chars
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- (isa, insnbuf, (unsigned char *) fragP->fr_opcode + addi_offset, 0);
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-
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- set_expr_const (&addmi_insn.tok[2], loop_length_hi);
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- tinsn_to_insnbuf (&addmi_insn, insnbuf);
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- xtensa_insnbuf_to_chars
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- (isa, insnbuf, (unsigned char *) fragP->fr_opcode + addmi_offset, 0);
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-
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- /* Walk through all of the frags from here to the loop end
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- and mark them as no_transform to keep them from being modified
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- by the linker. If we ever have a relocation for the
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- addi/addmi of the difference of two symbols we can remove this. */
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-
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- target_count = 0;
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- for (next_fragP = fragP; next_fragP != NULL;
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- next_fragP = next_fragP->fr_next)
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- {
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- next_fragP->tc_frag_data.is_no_transform = TRUE;
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- if (next_fragP->tc_frag_data.is_loop_target)
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- target_count++;
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- if (target_count == 2)
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- break;
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- }
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-}
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-
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/* A map that keeps information on a per-subsegment basis. This is
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maintained during initial assembly, but is invalid once the
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diff --git a/gas/config/xtensa-relax.c b/gas/config/xtensa-relax.c
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index cb296ed85ed2..daf15d52c259 100644
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--- a/gas/config/xtensa-relax.c
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+++ b/gas/config/xtensa-relax.c
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@@ -87,13 +87,7 @@
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when the first and second operands are not the same as specified
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by the "| %at!=%as" precondition clause.
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{"l32i %at,%as,%imm | %at!=%as",
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- "LITERAL %imm; l32r %at,%LITERAL; add %at,%at,%as; l32i %at,%at,0"}
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-
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- There is special case for loop instructions here, but because we do
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- not currently have the ability to represent the difference of two
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- symbols, the conversion requires special code in the assembler to
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- write the operands of the addi/addmi pair representing the
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- difference of the old and new loop end label. */
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+ "LITERAL %imm; l32r %at,%LITERAL; add %at,%at,%as; l32i %at,%at,0"} */
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#include "as.h"
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#include "xtensa-isa.h"
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@@ -306,44 +300,83 @@ static string_pattern_pair widen_spec_list[] =
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{"l32i %at,%as,%imm | %at!=%as ? IsaUseConst16",
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"const16 %at,HI16U(%imm); const16 %at,LOW16U(%imm); add %at,%at,%as; l32i %at,%at,0"},
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- /* This is only PART of the loop instruction. In addition,
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- hardcoded into its use is a modification of the final operand in
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- the instruction in bytes 9 and 12. */
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- {"loop %as,%label | %as!=1 ? IsaUseLoops",
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+ /* Widening loops with literals. */
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+ {"loop %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
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+ "loop %as,%LABEL;"
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+ "rsr.lend %as;" /* LEND */
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+ "wsr.lbeg %as;" /* LBEG */
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+ "LITERAL %label;"
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+ "l32r %as, %LITERAL;"
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+ "nop;"
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+ "wsr.lend %as;"
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+ "isync;"
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+ "rsr.lcount %as;" /* LCOUNT */
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+ "addi %as, %as, 1;"
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+ "LABEL"},
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+ {"loopgtz %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
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+ "beqz %as,%label;"
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+ "bltz %as,%label;"
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+ "loopgtz %as,%LABEL;"
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+ "rsr.lend %as;" /* LEND */
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+ "wsr.lbeg %as;" /* LBEG */
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+ "LITERAL %label;"
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+ "l32r %as, %LITERAL;"
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+ "nop;"
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+ "wsr.lend %as;"
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+ "isync;"
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+ "rsr.lcount %as;" /* LCOUNT */
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+ "addi %as, %as, 1;"
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+ "LABEL"},
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+ {"loopnez %as,%label | %as!=1 ? IsaUseLoops ? IsaUseL32R",
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+ "beqz %as,%label;"
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+ "loopnez %as,%LABEL;"
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+ "rsr.lend %as;" /* LEND */
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+ "wsr.lbeg %as;" /* LBEG */
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+ "LITERAL %label;"
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+ "l32r %as, %LITERAL;"
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+ "nop;"
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+ "wsr.lend %as;"
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+ "isync;"
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+ "rsr.lcount %as;" /* LCOUNT */
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+ "addi %as, %as, 1;"
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+ "LABEL"},
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+
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+ /* Widening loops with const16. */
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+ {"loop %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
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"loop %as,%LABEL;"
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"rsr.lend %as;" /* LEND */
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"wsr.lbeg %as;" /* LBEG */
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- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
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- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
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+ "const16 %as,HI16U(%label);"
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+ "const16 %as,LOW16U(%label);"
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"wsr.lend %as;"
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"isync;"
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"rsr.lcount %as;" /* LCOUNT */
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- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
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+ "addi %as, %as, 1;"
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"LABEL"},
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- {"loopgtz %as,%label | %as!=1 ? IsaUseLoops",
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+ {"loopgtz %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
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"beqz %as,%label;"
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"bltz %as,%label;"
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"loopgtz %as,%LABEL;"
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"rsr.lend %as;" /* LEND */
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"wsr.lbeg %as;" /* LBEG */
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- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
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- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
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+ "const16 %as,HI16U(%label);"
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+ "const16 %as,LOW16U(%label);"
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"wsr.lend %as;"
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"isync;"
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"rsr.lcount %as;" /* LCOUNT */
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- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
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+ "addi %as, %as, 1;"
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"LABEL"},
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- {"loopnez %as,%label | %as!=1 ? IsaUseLoops",
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+ {"loopnez %as,%label | %as!=1 ? IsaUseLoops ? IsaUseConst16",
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"beqz %as,%label;"
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"loopnez %as,%LABEL;"
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"rsr.lend %as;" /* LEND */
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"wsr.lbeg %as;" /* LBEG */
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- "addi %as, %as, 0;" /* lo8(%label-%LABEL1) */
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- "addmi %as, %as, 0;" /* mid8(%label-%LABEL1) */
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+ "const16 %as,HI16U(%label);"
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+ "const16 %as,LOW16U(%label);"
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"wsr.lend %as;"
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"isync;"
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"rsr.lcount %as;" /* LCOUNT */
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- "addi %as, %as, 1;" /* density -> addi.n %as, %as, 1 */
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+ "addi %as, %as, 1;"
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"LABEL"},
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/* Relaxing to wide branches. Order is important here. With wide
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--
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2.11.0
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