Fix PR15155: lost vadd/vsplat optimization.

During lowering of a BUILD_VECTOR, we look for opportunities to use a
vector splat.  When the splatted value fits in 5 signed bits, a single
splat does the job.  When it doesn't fit in 5 bits but does fit in 6,
and is an even value, we can splat on half the value and add the result
to itself.

This last optimization hasn't been working recently because of improved
constant folding.  To circumvent this, create a pseudo VADD_SPLAT that
can be expanded during instruction selection.

llvm-svn: 175632

1 files changed, 77 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/vaddsplat.ll b/llvm/test/CodeGen/PowerPC/vaddsplat.ll
new file mode 100644
index 00000000000..b4c16c1bf91
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/vaddsplat.ll
@@ -0,0 +1,77 @@
+; RUN: llc -O0 -mcpu=pwr7 <%s | FileCheck %s
+
+; Test optimization of build_vector into vadd/vsplt for 6-bit immediates.
+
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+%v4i32 = type <4 x i32>
+%v8i16 = type <8 x i16>
+%v16i8 = type <16 x i8>
+
+define void @test_v4i32_pos(%v4i32* %P, %v4i32* %S) {
+       %p = load %v4i32* %P
+       %r = add %v4i32 %p, < i32 18, i32 18, i32 18, i32 18 >
+       store %v4i32 %r, %v4i32* %S
+       ret void
+}
+
+; CHECK: test_v4i32_pos:
+; CHECK: vspltisw [[REG1:[0-9]+]], 9
+; CHECK: vadduwm {{[0-9]+}}, [[REG1]], [[REG1]]
+
+define void @test_v4i32_neg(%v4i32* %P, %v4i32* %S) {
+       %p = load %v4i32* %P
+       %r = add %v4i32 %p, < i32 -28, i32 -28, i32 -28, i32 -28 >
+       store %v4i32 %r, %v4i32* %S
+       ret void
+}
+
+; CHECK: test_v4i32_neg:
+; CHECK: vspltisw [[REG1:[0-9]+]], -14
+; CHECK: vadduwm {{[0-9]+}}, [[REG1]], [[REG1]]
+
+define void @test_v8i16_pos(%v8i16* %P, %v8i16* %S) {
+       %p = load %v8i16* %P
+       %r = add %v8i16 %p, < i16 30, i16 30, i16 30, i16 30, i16 30, i16 30, i16 30, i16 30 >
+       store %v8i16 %r, %v8i16* %S
+       ret void
+}
+
+; CHECK: test_v8i16_pos:
+; CHECK: vspltish [[REG1:[0-9]+]], 15
+; CHECK: vadduhm {{[0-9]+}}, [[REG1]], [[REG1]]
+
+define void @test_v8i16_neg(%v8i16* %P, %v8i16* %S) {
+       %p = load %v8i16* %P
+       %r = add %v8i16 %p, < i16 -32, i16 -32, i16 -32, i16 -32, i16 -32, i16 -32, i16 -32, i16 -32 >
+       store %v8i16 %r, %v8i16* %S
+       ret void
+}
+
+; CHECK: test_v8i16_neg:
+; CHECK: vspltish [[REG1:[0-9]+]], -16
+; CHECK: vadduhm {{[0-9]+}}, [[REG1]], [[REG1]]
+
+define void @test_v16i8_pos(%v16i8* %P, %v16i8* %S) {
+       %p = load %v16i8* %P
+       %r = add %v16i8 %p, < i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16, i8 16 >
+       store %v16i8 %r, %v16i8* %S
+       ret void
+}
+
+; CHECK: test_v16i8_pos:
+; CHECK: vspltisb [[REG1:[0-9]+]], 8
+; CHECK: vaddubm {{[0-9]+}}, [[REG1]], [[REG1]]
+
+define void @test_v16i8_neg(%v16i8* %P, %v16i8* %S) {
+       %p = load %v16i8* %P
+       %r = add %v16i8 %p, < i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18, i8 -18 >
+       store %v16i8 %r, %v16i8* %S
+       ret void
+}
+
+; CHECK: test_v16i8_neg:
+; CHECK: vspltisb [[REG1:[0-9]+]], -9
+; CHECK: vaddubm {{[0-9]+}}, [[REG1]], [[REG1]]
+