[InstCombine] add tests to show potential shuffle+insert folds

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280403 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/Transforms/InstCombine/insert-const-shuf.ll b/test/Transforms/InstCombine/insert-const-shuf.ll
new file mode 100644 (file)
index 0000000..ebdf428
--- /dev/null
+++ b/test/Transforms/InstCombine/insert-const-shuf.ll
@@ -0,0 +1,112 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -instcombine %s | FileCheck %s
+
+; TODO: Eliminate the insertelement.
+
+define <4 x float> @PR29126(<4 x float> %x) {
+; CHECK-LABEL: @PR29126(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.000000e+00, float 2.000000e+00, float undef>, <4 x i32> <i32 0, i32 5, i32 6, i32 undef>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <4 x float> [[SHUF]], float 4.200000e+01, i32 3
+; CHECK-NEXT:    ret <4 x float> [[INS]]
+;
+  %shuf = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.0, float 2.0, float undef>, <4 x i32> <i32 0, i32 5, i32 6, i32 3>
+  %ins = insertelement <4 x float> %shuf, float 42.0, i32 3
+  ret <4 x float> %ins
+}
+
+; TODO: A chain of inserts should collapse.
+
+define <4 x float> @twoInserts(<4 x float> %x) {
+; CHECK-LABEL: @twoInserts(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> %x, <4 x float> <float undef, float 0.000000e+00, float undef, float undef>, <4 x i32> <i32 0, i32 5, i32 undef, i32 undef>
+; CHECK-NEXT:    [[INS1:%.*]] = insertelement <4 x float> [[SHUF]], float 4.200000e+01, i32 2
+; CHECK-NEXT:    [[INS2:%.*]] = insertelement <4 x float> [[INS1]], float 1.100000e+01, i32 3
+; CHECK-NEXT:    ret <4 x float> [[INS2]]
+;
+  %shuf = shufflevector <4 x float> %x, <4 x float> zeroinitializer, <4 x i32> <i32 0, i32 5, i32 6, i32 3>
+  %ins1 = insertelement <4 x float> %shuf, float 42.0, i32 2
+  %ins2 = insertelement <4 x float> %ins1, float 11.0, i32 3
+  ret <4 x float> %ins2
+}
+
+; TODO: Transform an arbitrary shuffle with constant into a shuffle that is equivalant to a vector select.
+
+define <4 x float> @disguisedSelect(<4 x float> %x) {
+; CHECK-LABEL: @disguisedSelect(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.000000e+00, float 2.000000e+00, float undef>, <4 x i32> <i32 undef, i32 6, i32 5, i32 3>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <4 x float> [[SHUF]], float 4.000000e+00, i32 0
+; CHECK-NEXT:    ret <4 x float> [[INS]]
+;
+  %shuf = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.0, float 2.0, float 3.0>, <4 x i32> <i32 7, i32 6, i32 5, i32 3>
+  %ins = insertelement <4 x float> %shuf, float 4.0, i32 0
+  ret <4 x float> %ins
+}
+
+; TODO: Fold arbitrary (non-select-equivalent) shuffles if the new shuffle would have the same shuffle mask.
+
+define <4 x float> @notSelectButNoMaskDifference(<4 x float> %x) {
+; CHECK-LABEL: @notSelectButNoMaskDifference(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.000000e+00, float 2.000000e+00, float undef>, <4 x i32> <i32 1, i32 5, i32 6, i32 undef>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <4 x float> [[SHUF]], float 4.000000e+00, i32 3
+; CHECK-NEXT:    ret <4 x float> [[INS]]
+;
+  %shuf = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.0, float 2.0, float 3.0>, <4 x i32> <i32 1, i32 5, i32 6, i32 3>
+  %ins = insertelement <4 x float> %shuf, float 4.0, i32 3
+  ret <4 x float> %ins
+}
+
+; We purposely do not touch arbitrary (non-select-equivalent) shuffles because folding the insert may create a more expensive shuffle.
+
+define <4 x float> @tooRisky(<4 x float> %x) {
+; CHECK-LABEL: @tooRisky(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> %x, <4 x float> <float 1.000000e+00, float undef, float undef, float undef>, <4 x i32> <i32 1, i32 4, i32 4, i32 undef>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <4 x float> [[SHUF]], float 4.000000e+00, i32 3
+; CHECK-NEXT:    ret <4 x float> [[INS]]
+;
+  %shuf = shufflevector <4 x float> %x, <4 x float> <float 1.0, float undef, float undef, float undef>, <4 x i32> <i32 1, i32 4, i32 4, i32 4>
+  %ins = insertelement <4 x float> %shuf, float 4.0, i32 3
+  ret <4 x float> %ins
+}
+
+; Don't transform insert to shuffle if the original shuffle is not removed.
+; TODO: Ease the one-use restriction if the insert scalar would simplify the shuffle to a full vector constant?
+
+define <3 x float> @twoShufUses(<3 x float> %x) {
+; CHECK-LABEL: @twoShufUses(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <3 x float> %x, <3 x float> <float undef, float 1.000000e+00, float 2.000000e+00>, <3 x i32> <i32 0, i32 4, i32 5>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <3 x float> [[SHUF]], float 4.200000e+01, i2 1
+; CHECK-NEXT:    [[ADD:%.*]] = fadd <3 x float> [[SHUF]], [[INS]]
+; CHECK-NEXT:    ret <3 x float> [[ADD]]
+;
+  %shuf = shufflevector <3 x float> %x, <3 x float> <float undef, float 1.0, float 2.0>, <3 x i32> <i32 0, i32 4, i32 5>
+  %ins = insertelement <3 x float> %shuf, float 42.0, i2 1
+  %add = fadd <3 x float> %shuf, %ins
+  ret <3 x float> %add
+}
+
+; The inserted scalar constant index is out-of-bounds for the shuffle vector constant.
+
+define <5 x i8> @longerMask(<3 x i8> %x) {
+; CHECK-LABEL: @longerMask(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <3 x i8> %x, <3 x i8> <i8 undef, i8 1, i8 undef>, <5 x i32> <i32 2, i32 1, i32 4, i32 undef, i32 undef>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <5 x i8> [[SHUF]], i8 42, i17 4
+; CHECK-NEXT:    ret <5 x i8> [[INS]]
+;
+  %shuf = shufflevector <3 x i8> %x, <3 x i8> <i8 undef, i8 1, i8 2>, <5 x i32> <i32 2, i32 1, i32 4, i32 3, i32 0>
+  %ins = insertelement <5 x i8> %shuf, i8 42, i17 4
+  ret <5 x i8> %ins
+}
+
+; TODO: The inserted constant could get folded into the shuffle vector constant.
+
+define <3 x i8> @shorterMask(<5 x i8> %x) {
+; CHECK-LABEL: @shorterMask(
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <5 x i8> %x, <5 x i8> undef, <3 x i32> <i32 undef, i32 1, i32 4>
+; CHECK-NEXT:    [[INS:%.*]] = insertelement <3 x i8> [[SHUF]], i8 42, i21 0
+; CHECK-NEXT:    ret <3 x i8> [[INS]]
+;
+  %shuf = shufflevector <5 x i8> %x, <5 x i8> <i8 undef, i8 1, i8 2, i8 3, i8 4>, <3 x i32> <i32 2, i32 1, i32 4>
+  %ins = insertelement <3 x i8> %shuf, i8 42, i21 0
+  ret <3 x i8> %ins
+}
+