DAG: Combine (and (setne X, 0), (setne X, -1)) -> (setuge (add X, 1), 2)
A common idiom is to use zero and all-ones as sentinal values and to
check for both in a single conditional ("x != 0 && x != (unsigned)-1").
That generates code, for i32, like:
testl %edi, %edi
setne %al
cmpl $-1, %edi
setne %cl
andb %al, %cl
With this transform, we generate the simpler:
incl %edi
cmpl $1, %edi
seta %al
Similar improvements for other integer sizes and on other platforms. In
general, combining the two setcc instructions into one is better.
rdar://14689217
llvm-svn: 188315
2013-08-13 23:30:58 +02:00
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; RUN: llc < %s -mcpu=cortex-a8 -march=arm -asm-verbose=false | FileCheck %s
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define zeroext i1 @test0(i32 %x) nounwind {
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; CHECK-LABEL: test0:
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; CHECK-NEXT: add [[REG:(r[0-9]+)|(lr)]], r0, #1
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; CHECK-NEXT: mov r0, #0
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; CHECK-NEXT: cmp [[REG]], #1
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2013-08-22 11:57:11 +02:00
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; CHECK-NEXT: movwhi r0, #1
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DAG: Combine (and (setne X, 0), (setne X, -1)) -> (setuge (add X, 1), 2)
A common idiom is to use zero and all-ones as sentinal values and to
check for both in a single conditional ("x != 0 && x != (unsigned)-1").
That generates code, for i32, like:
testl %edi, %edi
setne %al
cmpl $-1, %edi
setne %cl
andb %al, %cl
With this transform, we generate the simpler:
incl %edi
cmpl $1, %edi
seta %al
Similar improvements for other integer sizes and on other platforms. In
general, combining the two setcc instructions into one is better.
rdar://14689217
llvm-svn: 188315
2013-08-13 23:30:58 +02:00
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; CHECK-NEXT: bx lr
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%cmp1 = icmp ne i32 %x, -1
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%not.cmp = icmp ne i32 %x, 0
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%.cmp1 = and i1 %cmp1, %not.cmp
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ret i1 %.cmp1
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}
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