194 lines
6.3 KiB
Diff
194 lines
6.3 KiB
Diff
Index: toolchain/gcc/4.3.2/901-backport-fix-for-bug-32044.patch
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===================================================================
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--- toolchain/gcc/4.3.2/901-backport-fix-for-bug-32044.patch (revision 0)
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+++ toolchain/gcc/4.3.2/901-backport-fix-for-bug-32044.patch (revision 0)
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@@ -0,0 +1,188 @@
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+Index: gcc-4.3.2/gcc/tree-scalar-evolution.c
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+===================================================================
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+--- gcc-4.3.2.orig/gcc/tree-scalar-evolution.c 2009-01-28 10:14:37.000000000 +0100
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++++ gcc-4.3.2/gcc/tree-scalar-evolution.c 2009-01-28 10:17:50.000000000 +0100
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+@@ -2716,6 +2716,50 @@
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+ scalar_evolution_info = NULL;
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+ }
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+
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++/* Returns true if the expression EXPR is considered to be too expensive
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++ for scev_const_prop. */
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++
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++bool
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++expression_expensive_p (tree expr)
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++{
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++ enum tree_code code;
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++
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++ if (is_gimple_val (expr))
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++ return false;
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++
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++ code = TREE_CODE (expr);
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++ if (code == TRUNC_DIV_EXPR
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++ || code == CEIL_DIV_EXPR
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++ || code == FLOOR_DIV_EXPR
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++ || code == ROUND_DIV_EXPR
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++ || code == TRUNC_MOD_EXPR
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++ || code == CEIL_MOD_EXPR
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++ || code == FLOOR_MOD_EXPR
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++ || code == ROUND_MOD_EXPR
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++ || code == EXACT_DIV_EXPR)
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++ {
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++ /* Division by power of two is usually cheap, so we allow it.
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++ Forbid anything else. */
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++ if (!integer_pow2p (TREE_OPERAND (expr, 1)))
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++ return true;
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++ }
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++
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++ switch (TREE_CODE_CLASS (code))
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++ {
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++ case tcc_binary:
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++ case tcc_comparison:
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++ if (expression_expensive_p (TREE_OPERAND (expr, 1)))
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++ return true;
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++
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++ /* Fallthru. */
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++ case tcc_unary:
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++ return expression_expensive_p (TREE_OPERAND (expr, 0));
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++
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++ default:
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++ return true;
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++ }
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++}
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++
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+ /* Replace ssa names for that scev can prove they are constant by the
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+ appropriate constants. Also perform final value replacement in loops,
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+ in case the replacement expressions are cheap.
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+@@ -2802,12 +2846,6 @@
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+ continue;
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+
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+ niter = number_of_latch_executions (loop);
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+- /* We used to check here whether the computation of NITER is expensive,
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+- and avoided final value elimination if that is the case. The problem
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+- is that it is hard to evaluate whether the expression is too
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+- expensive, as we do not know what optimization opportunities the
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+- the elimination of the final value may reveal. Therefore, we now
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+- eliminate the final values of induction variables unconditionally. */
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+ if (niter == chrec_dont_know)
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+ continue;
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+
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+@@ -2838,7 +2876,15 @@
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+ /* Moving the computation from the loop may prolong life range
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+ of some ssa names, which may cause problems if they appear
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+ on abnormal edges. */
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+- || contains_abnormal_ssa_name_p (def))
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++ || contains_abnormal_ssa_name_p (def)
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++ /* Do not emit expensive expressions. The rationale is that
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++ when someone writes a code like
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++
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++ while (n > 45) n -= 45;
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++
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++ he probably knows that n is not large, and does not want it
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++ to be turned into n %= 45. */
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++ || expression_expensive_p (def))
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+ continue;
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+
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+ /* Eliminate the PHI node and replace it by a computation outside
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+Index: gcc-4.3.2/gcc/tree-scalar-evolution.h
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+===================================================================
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+--- gcc-4.3.2.orig/gcc/tree-scalar-evolution.h 2009-01-28 10:22:47.000000000 +0100
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++++ gcc-4.3.2/gcc/tree-scalar-evolution.h 2009-01-28 10:23:10.000000000 +0100
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+@@ -35,6 +35,7 @@
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+ extern void scev_analysis (void);
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+ unsigned int scev_const_prop (void);
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+
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++bool expression_expensive_p (tree);
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+ extern bool simple_iv (struct loop *, tree, tree, affine_iv *, bool);
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+
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+ /* Returns the loop of the polynomial chrec CHREC. */
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+Index: gcc-4.3.2/gcc/testsuite/gcc.dg/pr34027-1.c
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+===================================================================
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+--- gcc-4.3.2.orig/gcc/testsuite/gcc.dg/pr34027-1.c 2009-01-28 10:24:09.000000000 +0100
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++++ gcc-4.3.2/gcc/testsuite/gcc.dg/pr34027-1.c 2009-01-28 10:24:43.000000000 +0100
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+@@ -8,5 +8,9 @@
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+ return ns;
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+ }
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+
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+-/* { dg-final { scan-tree-dump "ns % 10000" "optimized" } } */
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++/* This test was originally introduced to test that we transform
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++ to ns % 10000. See the discussion of PR 32044 why we do not do
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++ that anymore. */
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++/* { dg-final { scan-tree-dump-times "%" 0 "optimized" } } */
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++/* { dg-final { scan-tree-dump-times "/" 0 "optimized" } } */
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+ /* { dg-final { cleanup-tree-dump "optimized" } } */
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+Index: gcc-4.3.2/gcc/testsuite/gcc.dg/tree-ssa/pr32044.c
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+===================================================================
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+--- /dev/null 1970-01-01 00:00:00.000000000 +0000
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++++ gcc-4.3.2/gcc/testsuite/gcc.dg/tree-ssa/pr32044.c 2009-01-28 10:25:50.000000000 +0100
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+@@ -0,0 +1,55 @@
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++/* { dg-do compile } */
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++/* { dg-options "-O2 -fdump-tree-empty -fdump-tree-final_cleanup" } */
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++
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++int foo (int n)
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++{
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++ while (n >= 45)
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++ n -= 45;
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++
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++ return n;
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++}
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++
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++int bar (int n)
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++{
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++ while (n >= 64)
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++ n -= 64;
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++
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++ return n;
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++}
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++
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++int bla (int n)
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++{
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++ int i = 0;
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++
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++ while (n >= 45)
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++ {
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++ i++;
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++ n -= 45;
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++ }
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++
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++ return i;
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++}
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++
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++int baz (int n)
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++{
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++ int i = 0;
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++
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++ while (n >= 64)
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++ {
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++ i++;
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++ n -= 64;
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++ }
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++
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++ return i;
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++}
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++
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++/* The loops computing division/modulo by 64 should be eliminated. */
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++/* { dg-final { scan-tree-dump-times "Removing empty loop" 2 "empty" } } */
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++
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++/* There should be no division/modulo in the final dump (division and modulo
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++ by 64 are done using bit operations). */
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++/* { dg-final { scan-tree-dump-times "/" 0 "final_cleanup" } } */
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++/* { dg-final { scan-tree-dump-times "%" 0 "final_cleanup" } } */
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++
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++/* { dg-final { cleanup-tree-dump "empty" } } */
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++/* { dg-final { cleanup-tree-dump "final_cleanup" } } */
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+Index: gcc-4.3.2/gcc/tree-ssa-loop-ivopts.c
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+===================================================================
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+--- gcc-4.3.2.orig/gcc/tree-ssa-loop-ivopts.c 2009-01-28 10:26:04.000000000 +0100
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++++ gcc-4.3.2/gcc/tree-ssa-loop-ivopts.c 2009-01-28 10:27:09.000000000 +0100
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+@@ -3778,7 +3778,12 @@
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+ return false;
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+
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+ cand_value_at (loop, cand, use->stmt, nit, &bnd);
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++
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+ *bound = aff_combination_to_tree (&bnd);
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++ /* It is unlikely that computing the number of iterations using division
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++ would be more profitable than keeping the original induction variable. */
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++ if (expression_expensive_p (*bound))
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++ return false;
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+ return true;
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+ }
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