[FastISel][x86] Teach how to select SSE2/AVX bitcasts between 128/256-bit vector types.

This patch teaches FastIsel the following two things:
1) On SSE2, no instructions are needed for bitcasts between 128-bit vector types;
2) On AVX, no instructions are needed for bitcasts between 256-bit vector types.

Example:

  %1 = bitcast <4 x i31> %V to <2 x i64>

Before (-fast-isel -fast-isel-abort=1):

  FastIsel miss: %1 = bitcast <4 x i31> %V to <2 x i64>

Now we don't fall back to SelectionDAG and we correctly fold that computation
propagating the register associated to %V.

Differential Revision: http://reviews.llvm.org/D13347

llvm-svn: 249121

1 files changed, 244 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/fast-isel-bitcasts-avx.ll b/llvm/test/CodeGen/X86/fast-isel-bitcasts-avx.ll
new file mode 100644
index 00000000000..03cefbc8682
--- /dev/null
+++ b/llvm/test/CodeGen/X86/fast-isel-bitcasts-avx.ll
@@ -0,0 +1,244 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx -fast-isel -fast-isel-abort=1 -asm-verbose=0 | FileCheck %s
+;
+; Bitcasts between 256-bit vector types are no-ops since no instruction is
+; needed for the conversion.
+
+define <4 x i64> @v8i32_to_v4i64(<8 x i32> %a) {
+;CHECK-LABEL: v8i32_to_v4i64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x i32> %a to <4 x i64>
+  ret <4 x i64> %1
+}
+
+define <4 x i64> @v16i16_to_v4i64(<16 x i16> %a) {
+;CHECK-LABEL: v16i16_to_v4i64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <16 x i16> %a to <4 x i64>
+  ret <4 x i64> %1
+}
+
+define <4 x i64> @v32i8_to_v4i64(<32 x i8> %a) {
+;CHECK-LABEL: v32i8_to_v4i64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <32 x i8> %a to <4 x i64>
+  ret <4 x i64> %1
+}
+
+define <4 x i64> @v4f64_to_v4i64(<4 x double> %a) {
+;CHECK-LABEL: v4f64_to_v4i64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x double> %a to <4 x i64>
+  ret <4 x i64> %1
+}
+
+define <4 x i64> @v8f32_to_v4i64(<8 x float> %a) {
+;CHECK-LABEL: v8f32_to_v4i64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x float> %a to <4 x i64>
+  ret <4 x i64> %1
+}
+
+define <8 x i32> @v4i64_to_v8i32(<4 x i64> %a) {
+;CHECK-LABEL: v4i64_to_v8i32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x i64> %a to <8 x i32>
+  ret <8 x i32> %1
+}
+
+define <8 x i32> @v16i16_to_v8i32(<16 x i16> %a) {
+;CHECK-LABEL: v16i16_to_v8i32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <16 x i16> %a to <8 x i32>
+  ret <8 x i32> %1
+}
+
+define <8 x i32> @v32i8_to_v8i32(<32 x i8> %a) {
+;CHECK-LABEL: v32i8_to_v8i32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <32 x i8> %a to <8 x i32>
+  ret <8 x i32> %1
+}
+
+define <8 x i32> @v4f64_to_v8i32(<4 x double> %a) {
+;CHECK-LABEL: v4f64_to_v8i32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x double> %a to <8 x i32>
+  ret <8 x i32> %1
+}
+
+define <8 x i32> @v8f32_to_v8i32(<8 x float> %a) {
+;CHECK-LABEL: v8f32_to_v8i32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x float> %a to <8 x i32>
+  ret <8 x i32> %1
+}
+
+define <16 x i16> @v4i64_to_v16i16(<4 x i64> %a) {
+;CHECK-LABEL: v4i64_to_v16i16:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x i64> %a to <16 x i16>
+  ret <16 x i16> %1
+}
+
+define <16 x i16> @v8i32_to_v16i16(<8 x i32> %a) {
+;CHECK-LABEL: v8i32_to_v16i16:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x i32> %a to <16 x i16>
+  ret <16 x i16> %1
+}
+
+define <16 x i16> @v32i8_to_v16i16(<32 x i8> %a) {
+;CHECK-LABEL: v32i8_to_v16i16:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <32 x i8> %a to <16 x i16>
+  ret <16 x i16> %1
+}
+
+define <16 x i16> @v4f64_to_v16i16(<4 x double> %a) {
+;CHECK-LABEL: v4f64_to_v16i16:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x double> %a to <16 x i16>
+  ret <16 x i16> %1
+}
+
+define <16 x i16> @v8f32_to_v16i16(<8 x float> %a) {
+;CHECK-LABEL: v8f32_to_v16i16:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x float> %a to <16 x i16>
+  ret <16 x i16> %1
+}
+
+define <32 x i8> @v16i16_to_v32i8(<16 x i16> %a) {
+;CHECK-LABEL: v16i16_to_v32i8:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <16 x i16> %a to <32 x i8>
+  ret <32 x i8> %1
+}
+
+define <32 x i8> @v4i64_to_v32i8(<4 x i64> %a) {
+;CHECK-LABEL: v4i64_to_v32i8:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x i64> %a to <32 x i8>
+  ret <32 x i8> %1
+}
+
+define <32 x i8> @v8i32_to_v32i8(<8 x i32> %a) {
+;CHECK-LABEL: v8i32_to_v32i8:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x i32> %a to <32 x i8>
+  ret <32 x i8> %1
+}
+
+define <32 x i8> @v4f64_to_v32i8(<4 x double> %a) {
+;CHECK-LABEL: v4f64_to_v32i8:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x double> %a to <32 x i8>
+  ret <32 x i8> %1
+}
+
+define <32 x i8> @v8f32_to_v32i8(<8 x float> %a) {
+;CHECK-LABEL: v8f32_to_v32i8:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x float> %a to <32 x i8>
+  ret <32 x i8> %1
+}
+
+define <8 x float> @v32i8_to_v8f32(<32 x i8> %a) {
+;CHECK-LABEL: v32i8_to_v8f32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <32 x i8> %a to <8 x float>
+  ret <8 x float> %1
+}
+
+define <8 x float> @v16i16_to_v8f32(<16 x i16> %a) {
+;CHECK-LABEL: v16i16_to_v8f32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <16 x i16> %a to <8 x float>
+  ret <8 x float> %1
+}
+
+define <8 x float> @v4i64_to_v8f32(<4 x i64> %a) {
+;CHECK-LABEL: v4i64_to_v8f32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x i64> %a to <8 x float>
+  ret <8 x float> %1
+}
+
+define <8 x float> @v8i32_to_v8f32(<8 x i32> %a) {
+;CHECK-LABEL: v8i32_to_v8f32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x i32> %a to <8 x float>
+  ret <8 x float> %1
+}
+
+define <8 x float> @v4f64_to_v8f32(<4 x double> %a) {
+;CHECK-LABEL: v4f64_to_v8f32:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x double> %a to <8 x float>
+  ret <8 x float> %1
+}
+
+define <4 x double> @v8f32_to_v4f64(<8 x float> %a) {
+;CHECK-LABEL: v8f32_to_v4f64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x float> %a to <4 x double>
+  ret <4 x double> %1
+}
+
+define <4 x double> @v32i8_to_v4f64(<32 x i8> %a) {
+;CHECK-LABEL: v32i8_to_v4f64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <32 x i8> %a to <4 x double>
+  ret <4 x double> %1
+}
+
+define <4 x double> @v16i16_to_v4f64(<16 x i16> %a) {
+;CHECK-LABEL: v16i16_to_v4f64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <16 x i16> %a to <4 x double>
+  ret <4 x double> %1
+}
+
+define <4 x double> @v4i64_to_v4f64(<4 x i64> %a) {
+;CHECK-LABEL: v4i64_to_v4f64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <4 x i64> %a to <4 x double>
+  ret <4 x double> %1
+}
+
+define <4 x double> @v8i32_to_v4f64(<8 x i32> %a) {
+;CHECK-LABEL: v8i32_to_v4f64:
+;CHECK-NEXT: .cfi_startproc
+;CHECK-NEXT: ret
+  %1 = bitcast <8 x i32> %a to <4 x double>
+  ret <4 x double> %1
+}