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08762f9f1e
An identity COPY like this: %AL = COPY %AL, %EAX<imp-def> has no semantic effect, but encodes liveness information: Further users of %EAX only depend on this instruction even though it does not define the full register. Replace the COPY with a KILL instruction in those cases to maintain this liveness information. (This reverts a small part of r238588 but this time adds a comment explaining why a KILL instruction is useful). llvm-svn: 274952
217 lines
5.5 KiB
LLVM
217 lines
5.5 KiB
LLVM
; RUN: llc -mtriple=i686-unknown-linux-gnu -mattr=+cmov %s -o - | FileCheck %s --check-prefix=CHECK32
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; RUN: llc -mtriple=x86_64-unknown-linux-gnu -mattr=+cmov %s -o - | FileCheck %s --check-prefix=CHECK64
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; RUN: llc -mtriple=x86_64-pc-win32 -mattr=+cmov %s -o - | FileCheck %s --check-prefix=CHECKWIN64
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define i32 @one32_nooptsize() {
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entry:
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ret i32 1
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; When not optimizing for size, use mov.
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; CHECK32-LABEL: one32_nooptsize:
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; CHECK32: movl $1, %eax
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; CHECK32-NEXT: retl
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; CHECK64-LABEL: one32_nooptsize:
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; CHECK64: movl $1, %eax
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; CHECK64-NEXT: retq
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}
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define i32 @one32() optsize {
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entry:
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ret i32 1
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; CHECK32-LABEL: one32:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: incl %eax
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; CHECK32-NEXT: retl
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; FIXME: Figure out the best approach in 64-bit mode.
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; CHECK64-LABEL: one32:
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; CHECK64: movl $1, %eax
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; CHECK64-NEXT: retq
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}
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define i32 @one32_minsize() minsize {
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entry:
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ret i32 1
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; On 32-bit, xor-inc is preferred over push-pop.
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; CHECK32-LABEL: one32_minsize:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: incl %eax
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; CHECK32-NEXT: retl
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; On 64-bit we don't do xor-inc yet, so push-pop it is. Note that we have to
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; pop into a 64-bit register even when we just need 32 bits.
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; CHECK64-LABEL: one32_minsize:
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; CHECK64: pushq $1
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; CHECK64: .cfi_adjust_cfa_offset 8
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; CHECK64: popq %rax
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; CHECK64: .cfi_adjust_cfa_offset -8
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; CHECK64-NEXT: retq
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; On Win64 we can't adjust the stack unless there's a frame pointer.
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; CHECKWIN64-LABEL: one32_minsize:
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; CHECKWIN64: movl $1, %eax
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; CHECKWIN64-NEXT: retq
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}
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define i32 @pr26023() minsize {
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entry:
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%x = alloca [120 x i8]
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%0 = getelementptr inbounds [120 x i8], [120 x i8]* %x, i64 0, i64 0
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call void asm sideeffect "", "imr,~{memory},~{dirflag},~{fpsr},~{flags}"(i8* %0)
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%arrayidx = getelementptr inbounds [120 x i8], [120 x i8]* %x, i64 0, i64 119
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store volatile i8 -2, i8* %arrayidx
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call void asm sideeffect "", "r,~{dirflag},~{fpsr},~{flags}"(i32 5)
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%1 = load volatile i8, i8* %arrayidx
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%conv = sext i8 %1 to i32
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ret i32 %conv
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; The function writes to the redzone, so push/pop cannot be used.
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; CHECK64-LABEL: pr26023:
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; CHECK64: movl $5, %ecx
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; CHECK64: retq
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; 32-bit X86 doesn't have a redzone.
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; CHECK32-LABEL: pr26023:
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; CHECK32: pushl $5
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; CHECK32: popl %ecx
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; CHECK32: retl
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}
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define i64 @one64_minsize() minsize {
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entry:
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ret i64 1
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; On 64-bit we don't do xor-inc yet, so push-pop it is.
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; CHECK64-LABEL: one64_minsize:
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; CHECK64: pushq $1
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; CHECK64: .cfi_adjust_cfa_offset 8
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; CHECK64: popq %rax
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; CHECK64: .cfi_adjust_cfa_offset -8
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; CHECK64-NEXT: retq
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; On Win64 we can't adjust the stack unless there's a frame pointer.
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; CHECKWIN64-LABEL: one64_minsize:
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; CHECKWIN64: movl $1, %eax
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; CHECKWIN64-NEXT: retq
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}
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define i32 @minus_one32() optsize {
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entry:
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ret i32 -1
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; CHECK32-LABEL: minus_one32:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: decl %eax
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; CHECK32-NEXT: retl
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}
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define i32 @minus_one32_minsize() minsize {
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entry:
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ret i32 -1
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; xor-dec is preferred over push-pop.
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; CHECK32-LABEL: minus_one32_minsize:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: decl %eax
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; CHECK32-NEXT: retl
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}
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define i16 @one16() optsize {
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entry:
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ret i16 1
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; CHECK32-LABEL: one16:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: incl %eax
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; CHECK32-NEXT: # kill
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; CHECK32-NEXT: retl
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}
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define i16 @minus_one16() optsize {
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entry:
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ret i16 -1
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; CHECK32-LABEL: minus_one16:
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: decl %eax
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; CHECK32-NEXT: # kill
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; CHECK32-NEXT: retl
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}
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define i32 @minus_five32() minsize {
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entry:
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ret i32 -5
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; CHECK32-LABEL: minus_five32:
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; CHECK32: pushl $-5
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; CHECK32: popl %eax
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; CHECK32: retl
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}
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define i64 @minus_five64() minsize {
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entry:
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ret i64 -5
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; CHECK64-LABEL: minus_five64:
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; CHECK64: pushq $-5
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; CHECK64: .cfi_adjust_cfa_offset 8
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; CHECK64: popq %rax
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; CHECK64: .cfi_adjust_cfa_offset -8
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; CHECK64: retq
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}
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define i32 @rematerialize_minus_one() optsize {
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entry:
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; Materialize -1 (thiscall forces it into %ecx).
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tail call x86_thiscallcc void @f(i32 -1)
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; Clobber all registers except %esp, leaving nowhere to store the -1 besides
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; spilling it to the stack.
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tail call void asm sideeffect "", "~{eax},~{ebx},~{ecx},~{edx},~{edi},~{esi},~{ebp},~{dirflag},~{fpsr},~{flags}"()
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; -1 should be re-materialized here instead of getting spilled above.
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ret i32 -1
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; CHECK32-LABEL: rematerialize_minus_one
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; CHECK32: xorl %ecx, %ecx
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; CHECK32-NEXT: decl %ecx
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; CHECK32: calll
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; CHECK32: xorl %eax, %eax
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; CHECK32-NEXT: decl %eax
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; CHECK32-NOT: %eax
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; CHECK32: retl
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}
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define i32 @rematerialize_minus_one_eflags(i32 %x) optsize {
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entry:
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; Materialize -1 (thiscall forces it into %ecx).
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tail call x86_thiscallcc void @f(i32 -1)
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; Clobber all registers except %esp, leaving nowhere to store the -1 besides
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; spilling it to the stack.
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tail call void asm sideeffect "", "~{eax},~{ebx},~{ecx},~{edx},~{edi},~{esi},~{ebp},~{dirflag},~{fpsr},~{flags}"()
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; Define eflags.
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%a = icmp ne i32 %x, 123
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%b = zext i1 %a to i32
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; Cause -1 to be rematerialized right in front of the cmov, which needs eflags.
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; It must therefore not use the xor-dec lowering.
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%c = select i1 %a, i32 %b, i32 -1
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ret i32 %c
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; CHECK32-LABEL: rematerialize_minus_one_eflags
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; CHECK32: xorl %ecx, %ecx
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; CHECK32-NEXT: decl %ecx
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; CHECK32: calll
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; CHECK32: cmpl
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; CHECK32: setne
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; CHECK32-NOT: xorl
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; CHECK32: movl $-1
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; CHECK32: cmov
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; CHECK32: retl
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}
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declare x86_thiscallcc void @f(i32)
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