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Diffstat (limited to 'test/CodeGen/X86/copy-propagation.ll')
| -rw-r--r-- | test/CodeGen/X86/copy-propagation.ll | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/test/CodeGen/X86/copy-propagation.ll b/test/CodeGen/X86/copy-propagation.ll new file mode 100644 index 000000000000..19421a06fa82 --- /dev/null +++ b/test/CodeGen/X86/copy-propagation.ll @@ -0,0 +1,44 @@ +; 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<undef> +; 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<undef> +; 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 +} |