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[X86][MMX] Add test showing bad stack spill of shift value 

i32 is spilled to stack but 64-bit mmx is reloaded - leaving garbage in the other half of the register

llvm-svn: 297471
This commit is contained in:
Simon Pilgrim 2017-03-10 15:53:41 +00:00
parent 63ad95aee6
commit caa9172ba7
1 changed files with 41 additions and 0 deletions
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41
llvm/test/CodeGen/X86/mmx-fold-load.ll
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@ -562,3 +562,44 @@ entry:
ret i64 %s
}
declare x86_mmx @llvm.x86.mmx.psrl.q(x86_mmx, x86_mmx)
; FIXME: Show issue with storing i32 to stack and then reloading as x86_mmx
; which will lead to garbage in the other 32-bits.
define i64 @test_psrlq_by_volatile_shift_amount(x86_mmx %t) nounwind {
; X86-LABEL: test_psrlq_by_volatile_shift_amount:
; X86: # BB#0: # %entry
; X86-NEXT: pushl %ebp
; X86-NEXT: movl %esp, %ebp
; X86-NEXT: andl $-8, %esp
; X86-NEXT: subl $16, %esp
; X86-NEXT: movl $1, {{[0-9]+}}(%esp)
; X86-NEXT: movd {{[0-9]+}}(%esp), %mm1
; X86-NEXT: psrlq %mm1, %mm0
; X86-NEXT: movq %mm0, {{[0-9]+}}(%esp)
; X86-NEXT: movl {{[0-9]+}}(%esp), %eax
; X86-NEXT: movl {{[0-9]+}}(%esp), %edx
; X86-NEXT: movl %ebp, %esp
; X86-NEXT: popl %ebp
; X86-NEXT: retl
;
; X64-LABEL: test_psrlq_by_volatile_shift_amount:
; X64: # BB#0: # %entry
; X64-NEXT: movl $1, -{{[0-9]+}}(%rsp)
; X64-NEXT: movd -{{[0-9]+}}(%rsp), %mm1
; X64-NEXT: psrlq %mm1, %mm0
; X64-NEXT: movd %mm0, %rax
; X64-NEXT: retq
entry:
%0 = alloca i32, align 4
%1 = bitcast i32* %0 to i8*
call void @llvm.lifetime.start(i64 4, i8* nonnull %1)
store volatile i32 1, i32* %0, align 4
%2 = load volatile i32, i32* %0, align 4
%3 = tail call x86_mmx @llvm.x86.mmx.psrli.q(x86_mmx %t, i32 %2)
%4 = bitcast x86_mmx %3 to i64
call void @llvm.lifetime.end(i64 4, i8* nonnull %1)
ret i64 %4
}
declare void @llvm.lifetime.start(i64, i8* nocapture)
declare void @llvm.lifetime.end(i64, i8* nocapture)