X86: Don't crash if we can't decode the pshufb mask

Constant pool entries are uniqued by their contents regardless of their
type.  This means that a pshufb can have a shuffle mask which isn't a
simple array of bytes.

The code path which attempts to decode the mask didn't check for
failure, causing PR22559.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228979 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c11c8e3febd28253d0681b3750ca8c91f4bd8f6a..3c2e27af8f254bd2cf8b38209b59c3678f95cae6 100644 (file)
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5480,6 +5480,8 @@ static bool getTargetShuffleMask(SDNode *N, MVT VT,
 
     if (auto *C = dyn_cast<Constant>(MaskCP->getConstVal())) {
       DecodePSHUFBMask(C, Mask);
+      if (Mask.empty())
+        return false;
       break;
     }
 

diff --git a/test/CodeGen/X86/pshufb-mask-comments.ll b/test/CodeGen/X86/pshufb-mask-comments.ll
index 303c4a684761ce995bf8af36ace7cf1a4d28aba2..ca5a02ce8d3a1806834e7dc33c9638f271359cbf 100644 (file)
--- a/test/CodeGen/X86/pshufb-mask-comments.ll
+++ b/test/CodeGen/X86/pshufb-mask-comments.ll
@@ -37,4 +37,16 @@ define <16 x i8> @test4(<2 x i64>* %V) {
   ret <16 x i8> %1
 }
 
+define <16 x i8> @test5() {
+; CHECK-LABEL: test5
+; CHECK: pshufb {{.*}}
+  store <2 x i64> <i64 1, i64 0>, <2 x i64>* undef, align 16
+  %l = load <2 x i64>* undef, align 16
+  %shuffle = shufflevector <2 x i64> %l, <2 x i64> undef, <2 x i32> zeroinitializer
+  store <2 x i64> %shuffle, <2 x i64>* undef, align 16
+  %1 = load <16 x i8>* undef, align 16
+  %2 = call <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8> undef, <16 x i8> %1)
+  ret <16 x i8> %2
+}
+
 declare <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8>, <16 x i8>) nounwind readnone