[llvm] r194475 - SimplifyCFG: Use existing constant folding logic when forming switch tables.
Benjamin Kramer
benny.kra at googlemail.com
Tue Nov 12 04:24:36 PST 2013
Author: d0k
Date: Tue Nov 12 06:24:36 2013
New Revision: 194475
URL: http://llvm.org/viewvc/llvm-project?rev=194475&view=rev
Log:
SimplifyCFG: Use existing constant folding logic when forming switch tables.
Both simpler and more powerful than the hand-rolled folding logic.
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
llvm/trunk/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=194475&r1=194474&r2=194475&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Tue Nov 12 06:24:36 2013
@@ -19,6 +19,7 @@
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
@@ -3323,28 +3324,10 @@ static Constant *LookupConstant(Value *V
/// simple instructions such as binary operations where both operands are
/// constant or can be replaced by constants from the ConstantPool. Returns the
/// resulting constant on success, 0 otherwise.
-static Constant *ConstantFold(Instruction *I,
- const SmallDenseMap<Value*, Constant*>& ConstantPool) {
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
- Constant *A = LookupConstant(BO->getOperand(0), ConstantPool);
- if (!A)
- return 0;
- Constant *B = LookupConstant(BO->getOperand(1), ConstantPool);
- if (!B)
- return 0;
- return ConstantExpr::get(BO->getOpcode(), A, B);
- }
-
- if (CmpInst *Cmp = dyn_cast<CmpInst>(I)) {
- Constant *A = LookupConstant(I->getOperand(0), ConstantPool);
- if (!A)
- return 0;
- Constant *B = LookupConstant(I->getOperand(1), ConstantPool);
- if (!B)
- return 0;
- return ConstantExpr::getCompare(Cmp->getPredicate(), A, B);
- }
-
+static Constant *
+ConstantFold(Instruction *I,
+ const SmallDenseMap<Value *, Constant *> &ConstantPool,
+ const DataLayout *DL) {
if (SelectInst *Select = dyn_cast<SelectInst>(I)) {
Constant *A = LookupConstant(Select->getCondition(), ConstantPool);
if (!A)
@@ -3356,14 +3339,19 @@ static Constant *ConstantFold(Instructio
return 0;
}
- if (CastInst *Cast = dyn_cast<CastInst>(I)) {
- Constant *A = LookupConstant(I->getOperand(0), ConstantPool);
- if (!A)
+ SmallVector<Constant *, 4> COps;
+ for (unsigned N = 0, E = I->getNumOperands(); N != E; ++N) {
+ if (Constant *A = LookupConstant(I->getOperand(N), ConstantPool))
+ COps.push_back(A);
+ else
return 0;
- return ConstantExpr::getCast(Cast->getOpcode(), A, Cast->getDestTy());
}
- return 0;
+ if (CmpInst *Cmp = dyn_cast<CmpInst>(I))
+ return ConstantFoldCompareInstOperands(Cmp->getPredicate(), COps[0],
+ COps[1], DL);
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(), COps, DL);
}
/// GetCaseResults - Try to determine the resulting constant values in phi nodes
@@ -3375,7 +3363,8 @@ GetCaseResults(SwitchInst *SI,
ConstantInt *CaseVal,
BasicBlock *CaseDest,
BasicBlock **CommonDest,
- SmallVectorImpl<std::pair<PHINode*,Constant*> > &Res) {
+ SmallVectorImpl<std::pair<PHINode *, Constant *> > &Res,
+ const DataLayout *DL) {
// The block from which we enter the common destination.
BasicBlock *Pred = SI->getParent();
@@ -3394,7 +3383,7 @@ GetCaseResults(SwitchInst *SI,
} else if (isa<DbgInfoIntrinsic>(I)) {
// Skip debug intrinsic.
continue;
- } else if (Constant *C = ConstantFold(I, ConstantPool)) {
+ } else if (Constant *C = ConstantFold(I, ConstantPool, DL)) {
// Instruction is side-effect free and constant.
ConstantPool.insert(std::make_pair(I, C));
} else {
@@ -3718,7 +3707,7 @@ static bool SwitchToLookupTable(SwitchIn
typedef SmallVector<std::pair<PHINode*, Constant*>, 4> ResultsTy;
ResultsTy Results;
if (!GetCaseResults(SI, CaseVal, CI.getCaseSuccessor(), &CommonDest,
- Results))
+ Results, TD))
return false;
// Append the result from this case to the list for each phi.
@@ -3732,7 +3721,7 @@ static bool SwitchToLookupTable(SwitchIn
// Get the resulting values for the default case.
SmallVector<std::pair<PHINode*, Constant*>, 4> DefaultResultsList;
if (!GetCaseResults(SI, 0, SI->getDefaultDest(), &CommonDest,
- DefaultResultsList))
+ DefaultResultsList, TD))
return false;
for (size_t I = 0, E = DefaultResultsList.size(); I != E; ++I) {
PHINode *PHI = DefaultResultsList[I].first;
Modified: llvm/trunk/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll?rev=194475&r1=194474&r2=194475&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/X86/switch_to_lookup_table.ll Tue Nov 12 06:24:36 2013
@@ -711,7 +711,7 @@ return:
ret i32 %retval.0
}
-define i32 @cprop(i32 %x) {
+define i32 @cprop(i32 %x, i32 %y) {
entry:
switch i32 %x, label %sw.default [
i32 1, label %return
@@ -727,7 +727,8 @@ sw.bb1: br label %return
sw.bb2:
%and = and i32 %x, 1
- %tobool = icmp ne i32 %and, 0
+ %and.ptr = inttoptr i32 %and to i8*
+ %tobool = icmp ne i8* %and.ptr, null
%cond = select i1 %tobool, i32 -123, i32 456
%sub = sub nsw i32 %x, %cond
br label %return
@@ -735,13 +736,15 @@ sw.bb2:
sw.bb3:
%trunc = trunc i32 %x to i8
%sext = sext i8 %trunc to i32
+ %select.i = icmp sgt i32 %sext, 0
+ %select = select i1 %select.i, i32 %sext, i32 %y
br label %return
sw.default:
br label %return
return:
- %retval.0 = phi i32 [ 123, %sw.default ], [ %sext, %sw.bb3 ], [ %sub, %sw.bb2 ], [ 42, %sw.bb1 ], [ 5, %entry ]
+ %retval.0 = phi i32 [ 123, %sw.default ], [ %select, %sw.bb3 ], [ %sub, %sw.bb2 ], [ 42, %sw.bb1 ], [ 5, %entry ]
ret i32 %retval.0
; CHECK-LABEL: @cprop(
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