[PATCH] D83534: [X86][MMX] Optimize MMX shift intrinsics.

[Pengfei Wang via Phabricator via llvm-commits]

pengfei created this revision.
pengfei added reviewers: craig.topper, LuoYuanke.
Herald added subscribers: llvm-commits, hiraditya.
Herald added a project: LLVM.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83534

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/mmx-intrinsics.ll


Index: llvm/test/CodeGen/X86/mmx-intrinsics.ll
===================================================================
--- llvm/test/CodeGen/X86/mmx-intrinsics.ll
+++ llvm/test/CodeGen/X86/mmx-intrinsics.ll
@@ -311,6 +311,19 @@
   ret i64 %4
 }
 
+define i64 @test72_2(<1 x i64> %a) nounwind readnone optsize ssp {
+; ALL-LABEL: @test72_2
+; ALL-NOT: psraw
+entry:
+  %0 = bitcast <1 x i64> %a to <4 x i16>
+  %mmx_var.i = bitcast <4 x i16> %0 to x86_mmx
+  %1 = tail call x86_mmx @llvm.x86.mmx.psrai.w(x86_mmx %mmx_var.i, i32 0) nounwind
+  %2 = bitcast x86_mmx %1 to <4 x i16>
+  %3 = bitcast <4 x i16> %2 to <1 x i64>
+  %4 = extractelement <1 x i64> %3, i32 0
+  ret i64 %4
+}
+
 declare x86_mmx @llvm.x86.mmx.psrli.q(x86_mmx, i32) nounwind readnone
 
 define i64 @test71(<1 x i64> %a) nounwind readnone optsize ssp {
@@ -339,6 +352,19 @@
   ret i64 %4
 }
 
+define i64 @test70_2(<1 x i64> %a) nounwind readnone optsize ssp {
+; ALL-LABEL: @test70_2
+; ALL-NOT: psrld
+entry:
+  %0 = bitcast <1 x i64> %a to <2 x i32>
+  %mmx_var.i = bitcast <2 x i32> %0 to x86_mmx
+  %1 = tail call x86_mmx @llvm.x86.mmx.psrli.d(x86_mmx %mmx_var.i, i32 0) nounwind
+  %2 = bitcast x86_mmx %1 to <2 x i32>
+  %3 = bitcast <2 x i32> %2 to <1 x i64>
+  %4 = extractelement <1 x i64> %3, i32 0
+  ret i64 %4
+}
+
 declare x86_mmx @llvm.x86.mmx.psrli.w(x86_mmx, i32) nounwind readnone
 
 define i64 @test69(<1 x i64> %a) nounwind readnone optsize ssp {
@@ -397,6 +423,19 @@
   ret i64 %4
 }
 
+define i64 @test66_2(<1 x i64> %a) nounwind readnone optsize ssp {
+; ALL-LABEL: @test66_2
+; ALL-NOT: psllw
+entry:
+  %0 = bitcast <1 x i64> %a to <4 x i16>
+  %mmx_var.i = bitcast <4 x i16> %0 to x86_mmx
+  %1 = tail call x86_mmx @llvm.x86.mmx.pslli.w(x86_mmx %mmx_var.i, i32 0) nounwind
+  %2 = bitcast x86_mmx %1 to <4 x i16>
+  %3 = bitcast <4 x i16> %2 to <1 x i64>
+  %4 = extractelement <1 x i64> %3, i32 0
+  ret i64 %4
+}
+
 declare x86_mmx @llvm.x86.mmx.psra.d(x86_mmx, x86_mmx) nounwind readnone
 
 define i64 @test65(<1 x i64> %a, <1 x i64> %b) nounwind readnone optsize ssp {
Index: llvm/lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- llvm/lib/Target/X86/X86ISelLowering.cpp
+++ llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -25236,6 +25236,9 @@
       // Clamp out of bounds shift amounts since they will otherwise be masked
       // to 8-bits which may make it no longer out of bounds.
       unsigned ShiftAmount = C->getAPIntValue().getLimitedValue(255);
+      if (ShiftAmount == 0)
+        return Op.getOperand(1);
+
       return DAG.getNode(ISD::INTRINSIC_WO_CHAIN, DL, Op.getValueType(),
                          Op.getOperand(0), Op.getOperand(1),
                          DAG.getTargetConstant(ShiftAmount, DL, MVT::i32));


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