[llvm-commits] [llvm] r46687 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/2008-01-29-AddICmp.ll
Nick Lewycky
nicholas at mxc.ca
Sun Feb 3 08:33:10 PST 2008
Author: nicholas
Date: Sun Feb 3 10:33:09 2008
New Revision: 46687
URL: http://llvm.org/viewvc/llvm-project?rev=46687&view=rev
Log:
There are some cases where icmp(add) can be folded into a new icmp. Handle them.
Added:
llvm/trunk/test/Transforms/InstCombine/2008-01-29-AddICmp.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=46687&r1=46686&r2=46687&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Sun Feb 3 10:33:09 2008
@@ -45,6 +45,7 @@
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Support/CallSite.h"
+#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/InstVisitor.h"
@@ -5704,6 +5705,37 @@
DivRHS))
return R;
break;
+
+ case Instruction::Add:
+ // Fold: icmp pred (add, X, C1), C2
+
+ if (!ICI.isEquality()) {
+ ConstantInt *LHSC = dyn_cast<ConstantInt>(LHSI->getOperand(1));
+ if (!LHSC) break;
+ const APInt &LHSV = LHSC->getValue();
+
+ ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV)
+ .subtract(LHSV);
+
+ if (ICI.isSignedPredicate()) {
+ if (CR.getLower().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0),
+ ConstantInt::get(CR.getUpper()));
+ } else if (CR.getUpper().isSignBit()) {
+ return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0),
+ ConstantInt::get(CR.getLower()));
+ }
+ } else {
+ if (CR.getLower().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0),
+ ConstantInt::get(CR.getUpper()));
+ } else if (CR.getUpper().isMinValue()) {
+ return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0),
+ ConstantInt::get(CR.getLower()));
+ }
+ }
+ }
+ break;
}
// Simplify icmp_eq and icmp_ne instructions with integer constant RHS.
Added: llvm/trunk/test/Transforms/InstCombine/2008-01-29-AddICmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/2008-01-29-AddICmp.ll?rev=46687&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/2008-01-29-AddICmp.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/2008-01-29-AddICmp.ll Sun Feb 3 10:33:09 2008
@@ -0,0 +1,19 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {a.off}
+
+define i1 @test1(i32 %a) {
+ %a.off = add i32 %a, 4 ; <i32> [#uses=1]
+ %C = icmp ult i32 %a.off, 4 ; <i1> [#uses=1]
+ ret i1 %C
+}
+
+define i1 @test2(i32 %a) {
+ %a.off = sub i32 %a, 4 ; <i32> [#uses=1]
+ %C = icmp ugt i32 %a.off, -5 ; <i1> [#uses=1]
+ ret i1 %C
+}
+
+define i1 @test3(i32 %a) {
+ %a.off = add i32 %a, 4 ; <i32> [#uses=1]
+ %C = icmp slt i32 %a.off, 2147483652 ; <i1> [#uses=1]
+ ret i1 %C
+}
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