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llvm-project/llvm/test/CodeGen/ARM/setcc-sentinals.ll

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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
2013-08-14 05:30:58 +08:00
; RUN: llc < %s -mcpu=cortex-a8 -march=arm -asm-verbose=false | FileCheck %s
define zeroext i1 @test0(i32 %x) nounwind {
; CHECK-LABEL: test0:
; CHECK-NEXT: add [[REG:(r[0-9]+)|(lr)]], r0, #1
; CHECK-NEXT: mov r0, #0
; CHECK-NEXT: cmp [[REG]], #1
ARM: use TableGen patterns to select CMOV operations. Back in the mists of time (2008), it seems TableGen couldn't handle the patterns necessary to match ARM's CMOV node that we convert select operations to, so we wrote a lot of fairly hairy C++ to do it for us. TableGen can deal with it now: there were a few minor differences to CodeGen (see tests), but nothing obviously worse that I could see, so we should probably address anything that *does* come up in a localised manner. llvm-svn: 188995
2013-08-22 17:57:11 +08:00
; CHECK-NEXT: movwhi r0, #1
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
2013-08-14 05:30:58 +08:00
; CHECK-NEXT: bx lr
%cmp1 = icmp ne i32 %x, -1
%not.cmp = icmp ne i32 %x, 0
%.cmp1 = and i1 %cmp1, %not.cmp
ret i1 %.cmp1
}