diff options
| author | Christophe Lyon <christophe.lyon@linaro.org> | 2016-04-08 17:15:36 +0200 |
|---|---|---|
| committer | Linaro Code Review <review@review.linaro.org> | 2016-04-11 12:05:37 +0000 |
| commit | 07017c3304ec630a4d2b63fdf6346be9407f9153 (patch) | |
| tree | b391eaa6e8892ce344359436db7c162fa5f051cf | |
| parent | 20a2acfb0cecc500bb204243df95707386943e41 (diff) | |
gcc/
Backport from trunk r233941.
2016-03-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
PR rtl-optimization/69904
* config/arm/arm.c (arm_cannot_copy_insn_p):
Return true for load-exclusive instructions.
gcc/testsuite/
Backport from trunk r233941.
2016-03-03 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
PR rtl-optimization/69904
* gcc.target/arm/pr69904.c: New test.
Change-Id: I60c41d1a38f800183697a3c5440e884f6a789a26
| -rw-r--r-- | gcc/config/arm/arm.c | 20 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/arm/pr69904.c | 24 |
2 files changed, 43 insertions, 1 deletions
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c index 371528b0405..8f6679ed262 100644 --- a/gcc/config/arm/arm.c +++ b/gcc/config/arm/arm.c @@ -13233,7 +13233,11 @@ tls_mentioned_p (rtx x) } } -/* Must not copy any rtx that uses a pc-relative address. */ +/* Must not copy any rtx that uses a pc-relative address. + Also, disallow copying of load-exclusive instructions that + may appear after splitting of compare-and-swap-style operations + so as to prevent those loops from being transformed away from their + canonical forms (see PR 69904). */ static bool arm_cannot_copy_insn_p (rtx_insn *insn) @@ -13252,6 +13256,20 @@ arm_cannot_copy_insn_p (rtx_insn *insn) || XINT (x, 1) == UNSPEC_PIC_UNIFIED)) return true; } + + rtx set = single_set (insn); + if (set) + { + rtx src = SET_SRC (set); + if (GET_CODE (src) == ZERO_EXTEND) + src = XEXP (src, 0); + + /* Catch the load-exclusive and load-acquire operations. */ + if (GET_CODE (src) == UNSPEC_VOLATILE + && (XINT (src, 1) == VUNSPEC_LL + || XINT (src, 1) == VUNSPEC_LAX)) + return true; + } return false; } diff --git a/gcc/testsuite/gcc.target/arm/pr69904.c b/gcc/testsuite/gcc.target/arm/pr69904.c new file mode 100644 index 00000000000..24fe844d58e --- /dev/null +++ b/gcc/testsuite/gcc.target/arm/pr69904.c @@ -0,0 +1,24 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -marm" } */ +/* { dg-require-effective-target arm_arch_v7a_ok } */ +/* { dg-add-options arm_arch_v7a } */ + +/* Make sure that RTL optimizers don't do any unexpected transformations + on the compare_exchange loop. */ + +#include <stdatomic.h> + +atomic_uint foo; +atomic_uint bar; +int glob; + +int +main (void) +{ + glob = atomic_compare_exchange_strong (&foo, &bar, 0); + return glob; +} + +/* { dg-final { scan-assembler-times "dmb\tish" 2 } } */ +/* { dg-final { scan-assembler-times "ldrex\t" 1 } } */ +/* { dg-final { scan-assembler-times "strex\t" 1 } } */ |