An obfuscated splat is where the frontend poorly generates code for a splat
using several different shuffles to create the splat, i.e.,
%A = load <4 x float>* %in_ptr, align 16
%B = shufflevector <4 x float> %A, <4 x float> undef, <4 x i32> <i32 0, i32 0, i32 undef, i32 undef>
%C = shufflevector <4 x float> %B, <4 x float> %A, <4 x i32> <i32 0, i32 1, i32 4, i32 undef>
%D = shufflevector <4 x float> %C, <4 x float> %A, <4 x i32> <i32 0, i32 1, i32 2, i32 4>
llvm-svn: 166061
// If LHS's width is changed, shift the mask value accordingly.
// If newRHS == NULL, i.e. LHSOp0 == RHSOp0, we want to remap any
- // references to RHSOp0 to LHSOp0, so we don't need to shift the mask.
- if (eltMask >= 0 && newRHS != NULL)
+ // references from RHSOp0 to LHSOp0, so we don't need to shift the mask.
+ // If newRHS == newLHS, we want to remap any references from newRHS to
+ // newLHS so that we can properly identify splats that may occur due to
+ // obfuscation accross the two vectors.
+ if (eltMask >= 0 && newRHS != NULL && newLHS != newRHS)
eltMask += newLHSWidth;
}
--- /dev/null
+; RUN: opt -instcombine -S %s | FileCheck %s
+
+define void @test(<4 x float> *%in_ptr, <4 x float> *%out_ptr) {
+ %A = load <4 x float>* %in_ptr, align 16
+ %B = shufflevector <4 x float> %A, <4 x float> undef, <4 x i32> <i32 0, i32 0, i32 undef, i32 undef>
+ %C = shufflevector <4 x float> %B, <4 x float> %A, <4 x i32> <i32 0, i32 1, i32 4, i32 undef>
+ %D = shufflevector <4 x float> %C, <4 x float> %A, <4 x i32> <i32 0, i32 1, i32 2, i32 4>
+; CHECK: %D = shufflevector <4 x float> %A, <4 x float> undef, <4 x i32> zeroinitializer
+ store <4 x float> %D, <4 x float> *%out_ptr
+ ret void
+}