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| author | Richard Sandiford <rdsandiford@googlemail.com> | 2014-08-27 21:23:03 +0000 |
|---|---|---|
| committer | Richard Sandiford <rsandifo@gcc.gnu.org> | 2014-08-27 21:23:03 +0000 |
| commit | 109374e2fbfc38ae613f693d7f92bfc1beda7e4e (patch) | |
| tree | c235714f11418b1f758bec2f8e58e51f4d4780f4 /gcc/emit-rtl.c | |
| parent | b7679d96ec58fe7e67cbc535d1e3b055e40ac4f3 (diff) | |
| download | gcc-109374e2fbfc38ae613f693d7f92bfc1beda7e4e.tar.gz | |
emit-rtl.c (set_unique_reg_note): Discard notes with side effects.
gcc/
* emit-rtl.c (set_unique_reg_note): Discard notes with side effects.
From-SVN: r214609
Diffstat (limited to 'gcc/emit-rtl.c')
| -rw-r--r-- | gcc/emit-rtl.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c index 6cfaef6342a..9abe56ed7a7 100644 --- a/gcc/emit-rtl.c +++ b/gcc/emit-rtl.c @@ -5181,6 +5181,14 @@ set_unique_reg_note (rtx insn, enum reg_note kind, rtx datum) It serves no useful purpose and breaks eliminate_regs. */ if (GET_CODE (datum) == ASM_OPERANDS) return NULL_RTX; + + /* Notes with side effects are dangerous. Even if the side-effect + initially mirrors one in PATTERN (INSN), later optimizations + might alter the way that the final register value is calculated + and so move or alter the side-effect in some way. The note would + then no longer be a valid substitution for SET_SRC. */ + if (side_effects_p (datum)) + return NULL_RTX; break; default: |