[llvm] r174152 - Optimize shift lefts of a constant by a value plus constant into a single shift.
Nadav Rotem
nrotem at apple.com
Thu Jan 31 22:45:40 PST 2013
Author: nadav
Date: Fri Feb 1 00:45:40 2013
New Revision: 174152
URL: http://llvm.org/viewvc/llvm-project?rev=174152&view=rev
Log:
Optimize shift lefts of a constant by a value plus constant into a single shift.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
llvm/trunk/test/Transforms/InstCombine/shift.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp?rev=174152&r1=174151&r2=174152&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp Fri Feb 1 00:45:40 2013
@@ -709,6 +709,12 @@ Instruction *InstCombiner::visitShl(Bina
match(I.getOperand(1), m_Constant(C2)))
return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A);
+ // shl (c1 , add(y , c2)) -> (shl (shl(c1, c2)), y)
+ if (match(I.getOperand(0), m_Constant(C1)) &&
+ match(I.getOperand(1), m_Add(m_Value(A), m_Constant(C2)))) {
+ return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A);
+ }
+
return 0;
}
Modified: llvm/trunk/test/Transforms/InstCombine/shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/shift.ll?rev=174152&r1=174151&r2=174152&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/shift.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/shift.ll Fri Feb 1 00:45:40 2013
@@ -745,3 +745,23 @@ define i32 @test62(i32 %x) {
; CHECK: @test62
; CHECK: ashr exact i32 %x, 3
}
+
+; CHECK: @test63
+; CHECK: shl <4 x i32> <i32 1, i32 2, i32 4, i32 8>, %B
+define <4 x i32> @test63(i32 %n) {
+entry:
+ %K = insertelement <4 x i32> undef, i32 %n, i32 0
+ %B = shufflevector <4 x i32> %K, <4 x i32> undef, <4 x i32> zeroinitializer
+ %A = add <4 x i32> %B, <i32 0, i32 1, i32 2, i32 3>
+ %T = shl <4 x i32> <i32 1, i32 1, i32 1, i32 1>, %A
+ ret <4 x i32> %T
+}
+
+; CHECK: @test64
+; CHECK: shl i32 524288, %n
+define i32 @test64(i32 %n) {
+entry:
+ %A = add i32 %n, 19
+ %T = shl i32 1 , %A
+ ret i32 %T
+}
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