1; RUN: llc %s -mattr=+avx -o - | FileCheck %s 2; PR21743. 3 4target triple = "x86_64-pc-win32-elf" 5 6; Check that copy propagation conservatively assumes that undef register 7; can be rewritten by the backend to break false dependencies for the 8; hardware. 9; In this function we are in this situation: 10; reg1 = copy reg2 11; = inst reg2<undef> 12; reg2 = copy reg1 13; Copy propagation used to remove the last copy. 14; This is incorrect because the undef flag on reg2 in inst, allows next 15; passes to put whatever trashed value in reg2 that may help. 16; In practice we end up with this code: 17; reg1 = copy reg2 18; reg2 = 0 19; = inst reg2<undef> 20; reg2 = copy reg1 21; Therefore, removing the last copy is wrong. 22; 23; CHECK-LABEL: foo: 24; CHECK: movl $339752784, %e[[INDIRECT_CALL1:[a-z]+]] 25; CHECK: callq *%r[[INDIRECT_CALL1]] 26; Copy the result in a temporary. 27; Note: Technically the regalloc could have been smarter and this move not required, 28; which would have hidden the bug. 29; CHECK-NEXT: vmovapd %xmm0, [[TMP:%xmm[0-9]+]] 30; Crush xmm0. 31; CHECK-NEXT: vxorps %xmm0, %xmm0, %xmm0 32; CHECK: movl $339772768, %e[[INDIRECT_CALL2:[a-z]+]] 33; Set TMP in the first argument of the second call. 34; CHECK-NEXT: vmovapd [[TMP]], %xmm0 35; CHECK: callq *%r[[INDIRECT_CALL2]] 36; CHECK: retq 37define double @foo(i64 %arg) { 38top: 39 %tmp = call double inttoptr (i64 339752784 to double (double, double)*)(double 1.000000e+00, double 0.000000e+00) 40 %tmp1 = sitofp i64 %arg to double 41 call void inttoptr (i64 339772768 to void (double, double)*)(double %tmp, double %tmp1) 42 %tmp3 = fadd double %tmp1, %tmp 43 ret double %tmp3 44} 45