[InstCombine] Support (X | C1) & C2 --> (X & C2^(C1&C2)) | (C1&C2) for vector splats

Note the original code I deleted incorrectly listed this as (X | C1) & C2 --> (X & C2^(C1&C2)) | C1 Which is only valid if C1 is a subset of C2. This relied on SimplifyDemandedBits to remove any extra bits from C1 before we got to that code.

My new implementation avoids relying on that behavior so that it can be naively verified with alive.

Differential Revision: https://reviews.llvm.org/D36384

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310272 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 1699a0ce89cd1985b373e2fd8e6998413cbac898..db8e6ecb0bf0f11b3f3537001bacabb3859f9c83 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -126,21 +126,6 @@ Instruction *InstCombiner::OptAndOp(BinaryOperator *Op,
 
   switch (Op->getOpcode()) {
   default: break;
-  case Instruction::Or:
-    if (Op->hasOneUse()){
-      ConstantInt *TogetherCI = dyn_cast<ConstantInt>(Together);
-      if (TogetherCI && !TogetherCI->isZero()){
-        // (X | C1) & C2 --> (X & (C2^(C1&C2))) | C1
-        // NOTE: This reduces the number of bits set in the & mask, which
-        // can expose opportunities for store narrowing.
-        Together = ConstantExpr::getXor(AndRHS, Together);
-        Value *And = Builder.CreateAnd(X, Together);
-        And->takeName(Op);
-        return BinaryOperator::CreateOr(And, OpRHS);
-      }
-    }
-
-    break;
   case Instruction::Add:
     if (Op->hasOneUse()) {
       // Adding a one to a single bit bit-field should be turned into an XOR
@@ -1223,6 +1208,22 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
       return BinaryOperator::CreateXor(And, NewC);
     }
 
+    const APInt *OrC;
+    if (match(Op0, m_OneUse(m_Or(m_Value(X), m_APInt(OrC))))) {
+      // (X | C1) & C2 --> (X & C2^(C1&C2)) | (C1&C2)
+      // NOTE: This reduces the number of bits set in the & mask, which
+      // can expose opportunities for store narrowing for scalars.
+      // NOTE: SimplifyDemandedBits should have already removed bits from C1
+      // that aren't set in C2. Meaning we can replace (C1&C2) with C1 in
+      // above, but this feels safer.
+      APInt Together = *C & *OrC;
+      Value *And = Builder.CreateAnd(X, ConstantInt::get(I.getType(),
+                                                         Together ^ *C));
+      And->takeName(Op0);
+      return BinaryOperator::CreateOr(And, ConstantInt::get(I.getType(),
+                                                            Together));
+    }
+
     // If the mask is only needed on one incoming arm, push the 'and' op up.
     if (match(Op0, m_OneUse(m_Xor(m_Value(X), m_Value(Y)))) ||
         match(Op0, m_OneUse(m_Or(m_Value(X), m_Value(Y))))) {

diff --git a/test/Transforms/InstCombine/or.ll b/test/Transforms/InstCombine/or.ll
index fb56449ba4d46dc8d32430fd9a45a439c74cf04c..6ae52d454260566b0726deab01d28314ab84a346 100644 (file)
--- a/test/Transforms/InstCombine/or.ll
+++ b/test/Transforms/InstCombine/or.ll
@@ -268,6 +268,21 @@ define i32 @test30(i32 %A) {
   ret i32 %E
 }
 
+define <2 x i32> @test30vec(<2 x i32> %A) {
+; CHECK-LABEL: @test30vec(
+; CHECK-NEXT:    [[C:%.*]] = and <2 x i32> [[A:%.*]], <i32 -65536, i32 -65536>
+; CHECK-NEXT:    [[B:%.*]] = and <2 x i32> [[A]], <i32 7224, i32 7224>
+; CHECK-NEXT:    [[D:%.*]] = or <2 x i32> [[B]], <i32 32962, i32 32962>
+; CHECK-NEXT:    [[E:%.*]] = or <2 x i32> [[D]], [[C]]
+; CHECK-NEXT:    ret <2 x i32> [[E]]
+;
+  %B = or <2 x i32> %A, <i32 32962, i32 32962>
+  %C = and <2 x i32> %A, <i32 -65536, i32 -65536>
+  %D = and <2 x i32> %B, <i32 40186, i32 40186>
+  %E = or <2 x i32> %D, %C
+  ret <2 x i32> %E
+}
+
 ; PR4216
 define i64 @test31(i64 %A) {
 ; CHECK-LABEL: @test31(
@@ -285,6 +300,22 @@ define i64 @test31(i64 %A) {
   ret i64 %F
 }
 
+define <2 x i64> @test31vec(<2 x i64> %A) {
+; CHECK-LABEL: @test31vec(
+; CHECK-NEXT:    [[E:%.*]] = and <2 x i64> [[A:%.*]], <i64 4294908984, i64 4294908984>
+; CHECK-NEXT:    [[F:%.*]] = or <2 x i64> [[E]], <i64 32962, i64 32962>
+; CHECK-NEXT:    ret <2 x i64> [[F]]
+;
+  %B = or <2 x i64> %A, <i64 194, i64 194>
+  %D = and <2 x i64> %B, <i64 250, i64 250>
+
+  %C = or <2 x i64> %A, <i64 32768, i64 32768>
+  %E = and <2 x i64> %C, <i64 4294941696, i64 4294941696>
+
+  %F = or <2 x i64> %D, %E
+  ret <2 x i64> %F
+}
+
 ; codegen is mature enough to handle vector selects.
 define <4 x i32> @test32(<4 x i1> %and.i1352, <4 x i32> %vecinit6.i176, <4 x i32> %vecinit6.i191) {
 ; CHECK-LABEL: @test32(