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