46 lines
1.8 KiB
LLVM
46 lines
1.8 KiB
LLVM
; RUN: llc %s -mattr=+avx -o - | FileCheck %s
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; PR21743.
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target triple = "x86_64-pc-win32-elf"
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; Check that copy propagation conservatively assumes that undef register
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; can be rewritten by the backend to break false dependencies for the
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; hardware.
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; In this function we are in this situation:
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; reg1 = copy reg2
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; = inst reg2<undef>
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; reg2 = copy reg1
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; Copy propagation used to remove the last copy.
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; This is incorrect because the undef flag on reg2 in inst, allows next
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; passes to put whatever trashed value in reg2 that may help.
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; In practice we end up with this code:
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; reg1 = copy reg2
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; reg2 = 0
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; = inst reg2<undef>
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; reg2 = copy reg1
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; Therefore, removing the last copy is wrong.
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;
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; CHECK-LABEL: foo:
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; CHECK: movl $339752784, %e[[INDIRECT_CALL1:[a-z]+]]
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; CHECK: callq *%r[[INDIRECT_CALL1]]
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; Copy the result in a temporary.
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; Note: Technically the regalloc could have been smarter and this move not required,
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; which would have hidden the bug.
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; CHECK: vmovapd %xmm0, [[TMP:%xmm[0-9]+]]
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; Crush xmm0.
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; CHECK-NEXT: vxorps %xmm0, %xmm0, %xmm0
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; CHECK: movl $339772768, %e[[INDIRECT_CALL2:[a-z]+]]
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; Set TMP in the first argument of the second call.
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; CHECK-NEXT: vmovapd [[TMP]], %xmm0
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; CHECK: callq *%r[[INDIRECT_CALL2]]
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; CHECK: retq
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define double @foo(i64 %arg) {
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top:
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%tmp = call double inttoptr (i64 339752784 to double (double, double)*)(double 1.000000e+00, double 0.000000e+00)
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tail call void asm sideeffect "", "x,~{xmm1},~{xmm2},~{xmm3},~{xmm4},~{xmm5},~{xmm6},~{xmm7},~{xmm8},~{xmm9},~{xmm10},~{xmm11},~{xmm12},~{xmm13},~{xmm14},~{xmm15},~{dirflag},~{fpsr},~{flags}"(double %tmp)
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%tmp1 = sitofp i64 %arg to double
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call void inttoptr (i64 339772768 to void (double, double)*)(double %tmp, double %tmp1)
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%tmp3 = fadd double %tmp1, %tmp
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ret double %tmp3
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}
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