[PATCH] D146637: [InstCombine] Try to recognize bswap pattern when calling fshl

[Jun Zhang via Phabricator via llvm-commits]

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Alive2: https://alive2.llvm.org/ce/z/JiEXDg
Fixes: https://github.com/llvm/llvm-project/issues/60690

Signed-off-by: Jun Zhang <jun at junz.org>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146637

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
  llvm/test/Transforms/InstCombine/bswap.ll


Index: llvm/test/Transforms/InstCombine/bswap.ll
===================================================================
--- llvm/test/Transforms/InstCombine/bswap.ll
+++ llvm/test/Transforms/InstCombine/bswap.ll
@@ -932,17 +932,7 @@
 
 define i64 @call_fshl(i64 %result) {
 ; CHECK-LABEL: @call_fshl(
-; CHECK-NEXT:    [[AND_I:%.*]] = lshr i64 [[RESULT:%.*]], 8
-; CHECK-NEXT:    [[SHR_I:%.*]] = and i64 [[AND_I]], 71777214294589695
-; CHECK-NEXT:    [[AND1_I:%.*]] = shl i64 [[RESULT]], 8
-; CHECK-NEXT:    [[SHL_I:%.*]] = and i64 [[AND1_I]], -71777214294589696
-; CHECK-NEXT:    [[OR_I:%.*]] = or i64 [[SHR_I]], [[SHL_I]]
-; CHECK-NEXT:    [[AND_I7:%.*]] = shl i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHL_I8:%.*]] = and i64 [[AND_I7]], -281470681808896
-; CHECK-NEXT:    [[AND1_I9:%.*]] = lshr i64 [[OR_I]], 16
-; CHECK-NEXT:    [[SHR_I10:%.*]] = and i64 [[AND1_I9]], 281470681808895
-; CHECK-NEXT:    [[OR_I11:%.*]] = or i64 [[SHL_I8]], [[SHR_I10]]
-; CHECK-NEXT:    [[OR_I12:%.*]] = tail call i64 @llvm.fshl.i64(i64 [[OR_I11]], i64 [[OR_I11]], i64 32)
+; CHECK-NEXT:    [[OR_I12:%.*]] = call i64 @llvm.bswap.i64(i64 [[RESULT:%.*]])
 ; CHECK-NEXT:    ret i64 [[OR_I12]]
 ;
   %and.i = lshr i64 %result, 8
Index: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1234,9 +1234,8 @@
 
 /// If all arguments of the intrinsic are unary shuffles with the same mask,
 /// try to shuffle after the intrinsic.
-static Instruction *
-foldShuffledIntrinsicOperands(IntrinsicInst *II,
-                              InstCombiner::BuilderTy &Builder) {
+static Instruction *foldShuffledIntrinsicOperands(
+    IntrinsicInst *II, InstCombiner::BuilderTy &Builder, InstCombinerImpl &IC) {
   // TODO: This should be extended to handle other intrinsics like fshl, ctpop,
   //       etc. Use llvm::isTriviallyVectorizable() and related to determine
   //       which intrinsics are safe to shuffle?
@@ -1246,9 +1245,15 @@
   case Intrinsic::umax:
   case Intrinsic::umin:
   case Intrinsic::fma:
-  case Intrinsic::fshl:
   case Intrinsic::fshr:
     break;
+  case Intrinsic::fshl: {
+    if (Instruction *BitOp =
+            IC.matchBSwapOrBitReverse(*II, /*MatchBSwaps*/ true,
+                                      /*MatchBitReversals*/ true))
+      return BitOp;
+    break;
+  }
   default:
     return nullptr;
   }
@@ -3060,7 +3065,7 @@
   }
   }
 
-  if (Instruction *Shuf = foldShuffledIntrinsicOperands(II, Builder))
+  if (Instruction *Shuf = foldShuffledIntrinsicOperands(II, Builder, *this))
     return Shuf;
 
   // Some intrinsics (like experimental_gc_statepoint) can be used in invoke


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