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ba7c9948e8
"b + ((a < b) ? 1 : 0)" compiles into cmpl %esi, %edi adcl $0, %esi instead of cmpl %esi, %edi sbbl %eax, %eax andl $1, %eax addl %esi, %eax This saves a register, a false dependency on %eax (Intel's CPUs still don't ignore it) and it's shorter. llvm-svn: 131070
34 lines
861 B
LLVM
34 lines
861 B
LLVM
; RUN: llc < %s -march=x86 | FileCheck %s
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; <rdar://problem/8449754>
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define i32 @test1(i32 %sum, i32 %x) nounwind readnone ssp {
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entry:
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; CHECK: test1:
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; CHECK: cmpl %ecx, %eax
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; CHECK-NOT: addl
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; CHECK: adcl $0, %eax
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%add4 = add i32 %x, %sum
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%cmp = icmp ult i32 %add4, %x
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%inc = zext i1 %cmp to i32
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%z.0 = add i32 %add4, %inc
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ret i32 %z.0
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}
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; Instcombine transforms test1 into test2:
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; CHECK: test2:
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; CHECK: movl
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; CHECK-NEXT: addl
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; CHECK-NEXT: adcl $0
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; CHECK-NEXT: ret
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define i32 @test2(i32 %sum, i32 %x) nounwind readnone ssp {
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entry:
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%uadd = call { i32, i1 } @llvm.uadd.with.overflow.i32(i32 %x, i32 %sum)
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%0 = extractvalue { i32, i1 } %uadd, 0
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%cmp = extractvalue { i32, i1 } %uadd, 1
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%inc = zext i1 %cmp to i32
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%z.0 = add i32 %0, %inc
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ret i32 %z.0
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}
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declare { i32, i1 } @llvm.uadd.with.overflow.i32(i32, i32) nounwind readnone
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