From 142ff60219724cac948be5bef9fc4e6d1bfb8cfb Mon Sep 17 00:00:00 2001 From: Bin Cheng Date: Thu, 24 Aug 2017 15:38:39 +0000 Subject: [PATCH] re PR tree-optimization/81913 (wrong code at -O1) PR tree-optimization/81913 * tree-ssa-loop-niter.c (number_of_iterations_cond): Skip niter analysis when either IVs in condition can wrap. gcc/testsuite * gcc.c-torture/execute/pr81913.c: New test. * gcc.dg/tree-ssa/loop-niter-1.c: New test. * gcc.dg/tree-ssa/loop-niter-2.c: New test. From-SVN: r251337 --- gcc/ChangeLog | 6 ++++ gcc/testsuite/ChangeLog | 7 +++++ gcc/testsuite/gcc.c-torture/execute/pr81913.c | 27 ++++++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c | 31 +++++++++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c | 31 +++++++++++++++++++ gcc/tree-ssa-loop-niter.c | 6 ++-- 6 files changed, 106 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr81913.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 50ebb2b71ee..ac7cf9243c7 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2017-08-24 Bin Cheng + + PR tree-optimization/81913 + * tree-ssa-loop-niter.c (number_of_iterations_cond): Skip niter + analysis when either IVs in condition can wrap. + 2017-08-24 Uros Bizjak * dwarf2out.c (MAX_ARTIFICIAL_LABEL_BYTES): Increase to 40. diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 115d44550ad..1720a89b2e3 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2017-08-24 Bin Cheng + + PR tree-optimization/81913 + * gcc.c-torture/execute/pr81913.c: New test. + * gcc.dg/tree-ssa/loop-niter-1.c: New test. + * gcc.dg/tree-ssa/loop-niter-2.c: New test. + 2017-08-23 Richard Biener PR target/81921 diff --git a/gcc/testsuite/gcc.c-torture/execute/pr81913.c b/gcc/testsuite/gcc.c-torture/execute/pr81913.c new file mode 100644 index 00000000000..11eec4e1eaf --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr81913.c @@ -0,0 +1,27 @@ +/* PR tree-optimization/81913 */ + +typedef unsigned char u8; +typedef unsigned int u32; + +static u32 +b (u8 d, u32 e, u32 g) +{ + do + { + e += g + 1; + d--; + } + while (d >= (u8) e); + + return e; +} + +int +main (void) +{ + u32 x = b (1, -0x378704, ~0xba64fc); + if (x != 0xd93190d0) + __builtin_abort (); + return 0; +} + diff --git a/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c b/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c new file mode 100644 index 00000000000..16c76fe81bc --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-1.c @@ -0,0 +1,31 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -fdump-tree-sccp-details" } */ + +typedef unsigned char u8; +typedef unsigned int u32; + +static u32 +b (u8 d, u32 e, u32 g) +{ + do + { + e += g + 1; + d--; + } + while (d >= (u8) e); + + return e; +} + +int +main (void) +{ + u32 x = b (200, -0x378704, ~0xba64fc); + if (x != 0xe1ee4ca0) + __builtin_abort (); + + return 0; +} + +/* Niter analyzer should be able to compute niters for the loop. */ +/* { dg-final { scan-tree-dump "Replacing uses of: .* with: 3790490784" "sccp" { xfail *-*-* } } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c b/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c new file mode 100644 index 00000000000..2377e6caa72 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/loop-niter-2.c @@ -0,0 +1,31 @@ +/* { dg-do run } */ +/* { dg-options "-O2 -fdump-tree-sccp-details" } */ + +typedef unsigned char u8; +typedef unsigned int u32; + +static u32 +b (u8 d, u32 e, u32 g) +{ + do + { + e += g + 1; + d--; + } + while (d >= (u8) e); + + return e; +} + +int +main (void) +{ + u32 x = b (1, -0x378704, ~0xba64fc); + if (x != 0xd93190d0) + __builtin_abort (); + return 0; +} + +/* Niter analyzer should be able to compute niters for the loop even though + IV:d wraps. */ +/* { dg-final { scan-tree-dump "Replacing uses of: .* with: 3643904208" "sccp" { xfail *-*-* } } } */ diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 0d6d1019ac6..27244eb27c1 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -1728,7 +1728,7 @@ number_of_iterations_cond (struct loop *loop, provided that either below condition is satisfied: a) the test is NE_EXPR; - b) iv0.step - iv1.step is positive integer. + b) iv0.step - iv1.step is integer and iv0/iv1 don't overflow. This rarely occurs in practice, but it is simple enough to manage. */ if (!integer_zerop (iv0->step) && !integer_zerop (iv1->step)) @@ -1739,7 +1739,9 @@ number_of_iterations_cond (struct loop *loop, /* No need to check sign of the new step since below code takes care of this well. */ - if (code != NE_EXPR && TREE_CODE (step) != INTEGER_CST) + if (code != NE_EXPR + && (TREE_CODE (step) != INTEGER_CST + || !iv0->no_overflow || !iv1->no_overflow)) return false; iv0->step = step; -- 2.30.2