[llvm-commits] [llvm] r168615 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp test/Transforms/InstCombine/xor2.ll
Shuxin Yang
shuxin.llvm at gmail.com
Mon Nov 26 13:44:25 PST 2012
Author: shuxin_yang
Date: Mon Nov 26 15:44:25 2012
New Revision: 168615
URL: http://llvm.org/viewvc/llvm-project?rev=168615&view=rev
Log:
rdar://12329730 (defect 2)
Enhancement to InstCombine. Try to catch this opportunity:
---------------------------------------------------------------
((X^C1) >> C2) ^ C3 => (X>>C2) ^ ((C1>>C2)^C3)
where the subexpression "X ^ C1" has more than one uses, and
"(X^C1) >> C2" has single use.
----------------------------------------------------------------
Reviewed by Nadav (with minor change per his request).
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/test/Transforms/InstCombine/xor2.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=168615&r1=168614&r2=168615&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Mon Nov 26 15:44:25 2012
@@ -2159,6 +2159,27 @@
I.setOperand(1, NewRHS);
return &I;
}
+ } else if (Op0I->getOpcode() == Instruction::LShr) {
+ // ((X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
+ // E1 = "X ^ C1"
+ BinaryOperator *E1;
+ ConstantInt *C1;
+ if (Op0I->hasOneUse() &&
+ (E1 = dyn_cast<BinaryOperator>(Op0I->getOperand(0))) &&
+ E1->getOpcode() == Instruction::Xor &&
+ (C1 = dyn_cast<ConstantInt>(E1->getOperand(1)))) {
+ // fold (C1 >> C2) ^ C3
+ ConstantInt *C2 = Op0CI, *C3 = RHS;
+ APInt FoldConst = C1->getValue().lshr(C2->getValue());
+ FoldConst ^= C3->getValue();
+ // Prepare the two operands.
+ Value *Opnd0 = Builder->CreateLShr(E1->getOperand(0), C2);
+ Opnd0->takeName(Op0I);
+ cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc());
+ Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst);
+
+ return BinaryOperator::CreateXor(Opnd0, FoldVal);
+ }
}
}
}
Modified: llvm/trunk/test/Transforms/InstCombine/xor2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/xor2.ll?rev=168615&r1=168614&r2=168615&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/xor2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/xor2.ll Mon Nov 26 15:44:25 2012
@@ -51,3 +51,18 @@
; CHECK: %1 = ashr i32 %A, %B
; CHECK: ret i32 %1
}
+
+; defect-2 in rdar://12329730
+; (X^C1) >> C2) ^ C3 -> (X>>C2) ^ ((C1>>C2)^C3)
+; where the "X" has more than one use
+define i32 @test5(i32 %val1) {
+test5:
+ %xor = xor i32 %val1, 1234
+ %shr = lshr i32 %xor, 8
+ %xor1 = xor i32 %shr, 1
+ %add = add i32 %xor1, %xor
+ ret i32 %add
+; CHECK: @test5
+; CHECK: lshr i32 %val1, 8
+; CHECK: ret
+}
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