[X86DomainReassignment] Don't delete IMPLICIT_DEF nodes

Summary:
We cannot simply delete IMPLICIT_DEF nodes. They may be used
later (e.g. by a PHI) and deleting them will cause later passes (e.g.
LiveVariables) to crash. However, it seems fine to ignore them for
purposes of the domain reassignment (as we do with PHI).

Fixes PR37430
Fixes JuliaLang/julia#27080

Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D46797

llvm-svn: 332680

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/domain-reassignment-implicit-def.ll b/llvm/test/CodeGen/X86/domain-reassignment-implicit-def.ll
new file mode 100644
index 00000000000..1716b042d8e
--- /dev/null
+++ b/llvm/test/CodeGen/X86/domain-reassignment-implicit-def.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mcpu=skylake-avx512 -mtriple=x86_64-unknown-linux-gnu %s -o - | FileCheck %s
+
+; Check that the X86 Domain Reassignment pass doesn't drop IMPLICIT_DEF nodes,
+; which would later cause crashes (e.g. in LiveVariables) - see PR37430
+define void @domain_reassignment_implicit_def(i1 %cond, i8 *%mem, float %arg) {
+; CHECK:    vxorps %xmm1, %xmm1, %xmm1
+; CHECK:    vcmpneqss %xmm1, %xmm0, %k0
+; CHECK:    kmovb %k0, (%rsi)
+top:
+  br i1 %cond, label %L19, label %L15
+
+L15:                                              ; preds = %top
+  %tmp47 = fcmp une float 0.000000e+00, %arg
+  %tmp48 = zext i1 %tmp47 to i8
+  br label %L21
+
+L19:                                              ; preds = %top
+  br label %L21
+
+L21:                                              ; preds = %L19, %L15
+  %.sroa.0.0 = phi i8 [ undef, %L19 ], [ %tmp48, %L15 ]
+  store i8 %.sroa.0.0, i8* %mem, align 1
+  ret void
+}