https://gcc.gnu.org/g:a0e945888d973fc1a4a9d2944aa7e96d2a4d7581
commit r14-9379-ga0e945888d973fc1a4a9d2944aa7e96d2a4d7581 Author: Haochen Gui <guih...@gcc.gnu.org> Date: Fri Mar 8 09:30:35 2024 +0800 fwprop: Avoid volatile rtx to be propagated The patch for PR111267 (commit id 86de9b66480b710202a2898cf513db105d8c432f) which introduces an exception for propagation on single set insn. The propagation which might not be profitable (checked by profitable_p) is still allowed to be propagated to single set insn. It has a potential problem that a volatile operand might be propagated to a singel set insn. If the define insn is not eliminated after propagation, the volatile operand will be executed for multiple times. This patch fixes the problem by skipping volatile set source rtx in propagation. gcc/ * fwprop.cc (forward_propagate_into): Return false for volatile set source rtx. gcc/testsuite/ * gcc.target/powerpc/fwprop-1.c: New. Diff: --- gcc/fwprop.cc | 2 ++ gcc/testsuite/gcc.target/powerpc/fwprop-1.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/gcc/fwprop.cc b/gcc/fwprop.cc index 7872609b336..cb6fd6700ca 100644 --- a/gcc/fwprop.cc +++ b/gcc/fwprop.cc @@ -854,6 +854,8 @@ forward_propagate_into (use_info *use, bool reg_prop_only = false) rtx dest = SET_DEST (def_set); rtx src = SET_SRC (def_set); + if (volatile_refs_p (src)) + return false; /* Allow propagations into a loop only for reg-to-reg copies, since replacing one register by another shouldn't increase the cost. diff --git a/gcc/testsuite/gcc.target/powerpc/fwprop-1.c b/gcc/testsuite/gcc.target/powerpc/fwprop-1.c new file mode 100644 index 00000000000..07b207f980c --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/fwprop-1.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -fdump-rtl-fwprop1-details" } */ +/* { dg-final { scan-rtl-dump-not "propagating insn" "fwprop1" } } */ + +/* Verify that volatile asm operands doesn't try to be propagated. */ +long long foo () +{ + long long res; + __asm__ __volatile__( + "" + : "=r" (res) + : + : "memory"); + return res; +}