[PowerPC] PPCVSXFMAMutate should not segfault on undef input registers

When PPCVSXFMAMutate would look at the input addend register, it would get its
input value number. This would fail, however, if the register was undef,
causing a segfault. Don't segfault (just skip such FMA instructions).

Fixes the test case from PR24542 (although that may have been over-reduced).

llvm-svn: 245741

2 files changed, 38 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCVSXFMAMutate.cpp b/llvm/lib/Target/PowerPC/PPCVSXFMAMutate.cpp
index 974857556dc..f392b2572bc 100644
--- a/llvm/lib/Target/PowerPC/PPCVSXFMAMutate.cpp
+++ b/llvm/lib/Target/PowerPC/PPCVSXFMAMutate.cpp
@@ -103,6 +103,11 @@ protected:
 
         VNInfo *AddendValNo =
           LIS->getInterval(MI->getOperand(1).getReg()).Query(FMAIdx).valueIn();
+        if (!AddendValNo) {
+          // This can be null if the register is undef.
+          continue;
+        }
+
         MachineInstr *AddendMI = LIS->getInstructionFromIndex(AddendValNo->def);
 
         // The addend and this instruction must be in the same block.
diff --git a/llvm/test/CodeGen/PowerPC/vsx-fma-mutate-undef.ll b/llvm/test/CodeGen/PowerPC/vsx-fma-mutate-undef.ll
new file mode 100644
index 00000000000..e3f4001aa1d
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/vsx-fma-mutate-undef.ll
@@ -0,0 +1,33 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le-unknown-linux-gnu"
+
+; Function Attrs: nounwind
+define void @acosh_float8() #0 {
+entry:
+  br i1 undef, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %0 = tail call <4 x float> @llvm.fmuladd.v4f32(<4 x float> undef, <4 x float> <float 0x3FE62E4200000000, float 0x3FE62E4200000000, float 0x3FE62E4200000000, float 0x3FE62E4200000000>, <4 x float> undef) #0
+  %astype.i.i.74.i = bitcast <4 x float> %0 to <4 x i32>
+  %and.i.i.76.i = and <4 x i32> %astype.i.i.74.i, undef
+  %or.i.i.79.i = or <4 x i32> %and.i.i.76.i, undef
+  %astype5.i.i.80.i = bitcast <4 x i32> %or.i.i.79.i to <4 x float>
+  %1 = shufflevector <4 x float> %astype5.i.i.80.i, <4 x float> undef, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 undef, i32 undef, i32 undef, i32 undef>
+  %2 = shufflevector <8 x float> undef, <8 x float> %1, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 8, i32 9, i32 10, i32 11>
+  store <8 x float> %2, <8 x float>* undef, align 32
+  br label %if.end
+
+; CHECK-LABEL: @acosh_float8
+; CHECK: xvmaddasp
+
+if.end:                                           ; preds = %if.then, %entry
+  ret void
+}
+
+; Function Attrs: nounwind readnone
+declare <4 x float> @llvm.fmuladd.v4f32(<4 x float>, <4 x float>, <4 x float>) #1
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone }
+