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llvm-project/llvm/test/CodeGen/ARM/cbz-implicit-it-range.ll

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[ARM] Account for implicit IT when calculating inline asm size When deciding if it is safe to optimize a conditional branch to a CBZ or CBNZ the offsets of the BasicBlocks from the start of the function are estimated. For inline assembly the generic getInlineAsmLength() function is used to get a worst case estimate of the inline assembly by multiplying the number of instructions by the max instruction size of 4 bytes. This unfortunately doesn't take into account the generation of Thumb implicit IT instructions. In edge cases such as when all the instructions in the block are 4-bytes in size and there is an implicit IT then the size is underestimated. This can cause an out of range CBZ or CBNZ to be generated. The patch takes a conservative approach and assumes that every instruction in the inline assembly block may have an implicit IT. Fixes pr31805 Differential Revision: https://reviews.llvm.org/D52834 llvm-svn: 343960
2018-10-08 17:38:28 +08:00
;RUN: llc -O2 -mtriple=thumbv7a-linux-gnueabihf -arm-implicit-it=always %s -o - | FileCheck %s
;RUN: llc -O2 -mtriple=thumbv7a-linux-gnueabihf -no-integrated-as %s -o - | FileCheck %s
; Check that we do not produce a CBZ instruction to jump over the inline
; assembly as the distance is too far if the implicit IT instructions are
; added.
define void @f0(i32 %p1, i32 %p2, i32 %p3) nounwind {
entry:
%cmp = icmp eq i32 %p1, 0
br i1 %cmp, label %if.else, label %if.then
if.then:
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
tail call void asm sideeffect "movseq r0, #0\0A", ""()
br label %if.end
if.else:
tail call void asm sideeffect "nop\0A", ""()
br label %if.end
if.end:
ret void
}
; CHECK-LABEL: f0:
; CHECK: beq .LBB0_{{[0-9]+}}