[llvm-commits] [llvm] r52415 - /llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp
Chris Lattner
sabre at nondot.org
Tue Jun 17 10:06:44 PDT 2008
Author: lattner
Date: Tue Jun 17 12:06:43 2008
New Revision: 52415
URL: http://llvm.org/viewvc/llvm-project?rev=52415&view=rev
Log:
revert recent patch which is causing widespread breakage.
Modified:
llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp
Modified: llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp?rev=52415&r1=52414&r2=52415&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp Tue Jun 17 12:06:43 2008
@@ -21,7 +21,6 @@
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
-#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/Statistic.h"
@@ -141,14 +140,9 @@
}
-// Check to see if this function returns one or more constants. If so, replace
-// all callers that use those return values with the constant value. This will
-// leave in the actual return values and instructions, but deadargelim will
-// clean that up.
-//
-// Additionally if a function always returns one of its arguments directly,
-// callers will be updated to use the value they pass in directly instead of
-// using the return value.
+// Check to see if this function returns a constant. If so, replace all callers
+// that user the return value with the returned valued. If we can replace ALL
+// callers,
bool IPCP::PropagateConstantReturn(Function &F) {
if (F.getReturnType() == Type::VoidTy)
return false; // No return value.
@@ -162,65 +156,48 @@
SmallVector<Value *,4> RetVals;
const StructType *STy = dyn_cast<StructType>(F.getReturnType());
if (STy)
- for (unsigned i = 0, e = STy->getNumElements(); i < e; ++i)
- RetVals.push_back(UndefValue::get(STy->getElementType(i)));
+ RetVals.assign(STy->getNumElements(), 0);
else
- RetVals.push_back(UndefValue::get(F.getReturnType()));
+ RetVals.push_back(0);
- unsigned NumNonConstant = 0;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
- // Return type does not match operand type, this is an old style multiple
- // return
- bool OldReturn = (F.getReturnType() != RI->getOperand(0)->getType());
-
+ assert(RetVals.size() == RI->getNumOperands() &&
+ "Invalid ReturnInst operands!");
for (unsigned i = 0, e = RetVals.size(); i != e; ++i) {
- // Already found conflicting return values?
+ if (isa<UndefValue>(RI->getOperand(i)))
+ continue; // Ignore
+ Constant *C = dyn_cast<Constant>(RI->getOperand(i));
+ if (C == 0)
+ return false; // Does not return a constant.
+
Value *RV = RetVals[i];
- if (!RV)
- continue;
-
- // Find the returned value
- Value *V;
- if (!STy || OldReturn)
- V = RI->getOperand(i);
- else
- V = FindInsertedValue(RI->getOperand(0), i);
-
- if (V) {
- // Ignore undefs, we can change them into anything
- if (isa<UndefValue>(V))
- continue;
-
- // Try to see if all the rets return the same constant or argument.
- if (isa<Constant>(V) || isa<Argument>(V)) {
- if (isa<UndefValue>(RV)) {
- // No value found yet? Try the current one.
- RetVals[i] = V;
- continue;
- }
- // Returning the same value? Good.
- if (RV == V)
- continue;
- }
- }
- // Different or no known return value? Don't propagate this return
- // value.
- RetVals[i] = 0;
- // All values non constant? Stop looking.
- if (++NumNonConstant == RetVals.size())
- return false;
+ if (RV == 0)
+ RetVals[i] = C;
+ else if (RV != C)
+ return false; // Does not return the same constant.
}
}
- // If we got here, the function returns at least one constant value. Loop
- // over all users, replacing any uses of the return value with the returned
- // constant.
+ if (STy) {
+ for (unsigned i = 0, e = RetVals.size(); i < e; ++i)
+ if (RetVals[i] == 0)
+ RetVals[i] = UndefValue::get(STy->getElementType(i));
+ } else {
+ assert(RetVals.size() == 1);
+ if (RetVals[0] == 0)
+ RetVals[0] = UndefValue::get(F.getReturnType());
+ }
+
+ // If we got here, the function returns a constant value. Loop over all
+ // users, replacing any uses of the return value with the returned constant.
+ bool ReplacedAllUsers = true;
bool MadeChange = false;
for (Value::use_iterator UI = F.use_begin(), E = F.use_end(); UI != E; ++UI) {
// Make sure this is an invoke or call and that the use is for the callee.
if (!(isa<InvokeInst>(*UI) || isa<CallInst>(*UI)) ||
UI.getOperandNo() != 0) {
+ ReplacedAllUsers = false;
continue;
}
@@ -235,37 +212,28 @@
continue;
}
- for (Value::use_iterator I = Call->use_begin(), E = Call->use_end();
- I != E;) {
- Instruction *Ins = dyn_cast<Instruction>(*I);
-
- // Increment now, so we can remove the use
- ++I;
-
- // Not an instruction? Ignore
- if (!Ins)
- continue;
-
- // Find the index of the retval to replace with
- int index = -1;
- if (GetResultInst *GR = dyn_cast<GetResultInst>(Ins))
- index = GR->getIndex();
- else if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Ins))
- if (EV->hasIndices())
- index = *EV->idx_begin();
-
- // If this use uses a specific return value, and we have a replacement,
- // replace it.
- if (index != -1) {
- Value *New = RetVals[index];
- if (New) {
- if (Argument *A = dyn_cast<Argument>(New))
- // Was an argument returned? Then find the corresponding argument in
- // the call instruction and use that. Add 1 to the argument number
- // to skipp the first argument (the function itself).
- New = Call->getOperand(A->getArgNo() + 1);
- Ins->replaceAllUsesWith(New);
- Ins->eraseFromParent();
+ while (!Call->use_empty()) {
+ GetResultInst *GR = cast<GetResultInst>(Call->use_back());
+ GR->replaceAllUsesWith(RetVals[GR->getIndex()]);
+ GR->eraseFromParent();
+ }
+ }
+
+ // If we replace all users with the returned constant, and there can be no
+ // other callers of the function, replace the constant being returned in the
+ // function with an undef value.
+ if (ReplacedAllUsers && F.hasInternalLinkage()) {
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
+ for (unsigned i = 0, e = RetVals.size(); i < e; ++i) {
+ Value *RetVal = RetVals[i];
+ if (isa<UndefValue>(RetVal))
+ continue;
+ Value *RV = UndefValue::get(RetVal->getType());
+ if (RI->getOperand(i) != RV) {
+ RI->setOperand(i, RV);
+ MadeChange = true;
+ }
}
}
}
More information about the llvm-commits
mailing list