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[Bug target/51821] [4.5/4.6/4.7 Regression] 64bit > 32bit conversion produces incorrect results with optimizations
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 11 Jan 2012 11:28:08 +0000
- Subject: [Bug target/51821] [4.5/4.6/4.7 Regression] 64bit > 32bit conversion produces incorrect results with optimizations
- Auto-submitted: auto-generated
- References: <bug-51821-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51821
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Component|c |target
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-11 11:28:08 UTC ---
I believe this is a target issue. We produce
test:
.LFB0:
.cfi_startproc
movl 4(%esp), %ecx
movl $-1, %eax
xorl %edx, %edx
sall %cl, %eax
testb $32, %cl
cmovne %eax, %edx
cmovne %edx, %eax
ret
but as this is a SHIFT_COUNT_TRUNCATED target the sall instruction does
nothing, so shifting DImode by 32 is not implemented correctly on i?86
(ix86_split_ashl).