[llvm-commits] CVS: llvm/lib/Target/CBackend/Writer.cpp
Chris Lattner
lattner at cs.uiuc.edu
Sun May 9 15:41:01 PDT 2004
Changes in directory llvm/lib/Target/CBackend:
Writer.cpp updated: 1.173 -> 1.174
---
Log message:
syntactically loopify natural loops so that the GCC loop optimizer can find them. This should *dramatically* improve the performance of CBE compiled code on targets that depend on GCC's loop optimizations (like PPC)
---
Diffs of the changes: (+86 -53)
Index: llvm/lib/Target/CBackend/Writer.cpp
diff -u llvm/lib/Target/CBackend/Writer.cpp:1.173 llvm/lib/Target/CBackend/Writer.cpp:1.174
--- llvm/lib/Target/CBackend/Writer.cpp:1.173 Sun May 9 11:03:29 2004
+++ llvm/lib/Target/CBackend/Writer.cpp Sun May 9 15:41:32 2004
@@ -23,8 +23,9 @@
#include "llvm/SymbolTable.h"
#include "llvm/Intrinsics.h"
#include "llvm/IntrinsicLowering.h"
-#include "llvm/Analysis/FindUsedTypes.h"
#include "llvm/Analysis/ConstantsScanner.h"
+#include "llvm/Analysis/FindUsedTypes.h"
+#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Support/CFG.h"
@@ -59,6 +60,7 @@
std::ostream &Out;
IntrinsicLowering &IL;
Mangler *Mang;
+ LoopInfo *LI;
const Module *TheModule;
std::map<const Type *, std::string> TypeNames;
@@ -68,9 +70,16 @@
virtual const char *getPassName() const { return "C backend"; }
+ void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LoopInfo>();
+ AU.setPreservesAll();
+ }
+
virtual bool doInitialization(Module &M);
bool runOnFunction(Function &F) {
+ LI = &getAnalysis<LoopInfo>();
+
// Output all floating point constants that cannot be printed accurately.
printFloatingPointConstants(F);
@@ -84,7 +93,7 @@
// Free memory...
delete Mang;
TypeNames.clear();
- return true;
+ return false;
}
std::ostream &printType(std::ostream &Out, const Type *Ty,
@@ -105,6 +114,8 @@
void printFunctionSignature(const Function *F, bool Prototype);
void printFunction(Function &);
+ void printBasicBlock(BasicBlock *BB);
+ void printLoop(Loop *L);
void printConstant(Constant *CPV);
void printConstantArray(ConstantArray *CPA);
@@ -147,8 +158,13 @@
void visitReturnInst(ReturnInst &I);
void visitBranchInst(BranchInst &I);
void visitSwitchInst(SwitchInst &I);
- void visitInvokeInst(InvokeInst &I);
- void visitUnwindInst(UnwindInst &I);
+ void visitInvokeInst(InvokeInst &I) {
+ assert(0 && "Lowerinvoke pass didn't work!");
+ }
+
+ void visitUnwindInst(UnwindInst &I) {
+ assert(0 && "Lowerinvoke pass didn't work!");
+ }
void visitPHINode(PHINode &I);
void visitBinaryOperator(Instruction &I);
@@ -176,6 +192,8 @@
void outputLValue(Instruction *I) {
Out << " " << Mang->getValueName(I) << " = ";
}
+
+ bool isGotoCodeNecessary(BasicBlock *From, BasicBlock *To);
void printPHICopiesForSuccessors(BasicBlock *CurBlock,
unsigned Indent);
void printBranchToBlock(BasicBlock *CurBlock, BasicBlock *SuccBlock,
@@ -399,7 +417,7 @@
// compiler agreeing on the conversion process (which is pretty likely since we
// only deal in IEEE FP).
//
-bool isFPCSafeToPrint(const ConstantFP *CFP) {
+static bool isFPCSafeToPrint(const ConstantFP *CFP) {
#if HAVE_PRINTF_A
char Buffer[100];
sprintf(Buffer, "%a", CFP->getValue());
@@ -994,45 +1012,66 @@
// print the basic blocks
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- BasicBlock *Prev = BB->getPrev();
-
- // Don't print the label for the basic block if there are no uses, or if the
- // only terminator use is the predecessor basic block's terminator. We have
- // to scan the use list because PHI nodes use basic blocks too but do not
- // require a label to be generated.
- //
- bool NeedsLabel = false;
- for (Value::use_iterator UI = BB->use_begin(), UE = BB->use_end();
- UI != UE; ++UI)
- if (TerminatorInst *TI = dyn_cast<TerminatorInst>(*UI))
- if (TI != Prev->getTerminator() ||
- isa<SwitchInst>(Prev->getTerminator()) ||
- isa<InvokeInst>(Prev->getTerminator())) {
- NeedsLabel = true;
- break;
- }
-
- if (NeedsLabel) Out << Mang->getValueName(BB) << ":\n";
-
- // Output all of the instructions in the basic block...
- for (BasicBlock::iterator II = BB->begin(), E = --BB->end(); II != E; ++II){
- if (!isInlinableInst(*II) && !isDirectAlloca(II)) {
- if (II->getType() != Type::VoidTy)
- outputLValue(II);
- else
- Out << " ";
- visit(*II);
- Out << ";\n";
- }
+ if (Loop *L = LI->getLoopFor(BB)) {
+ if (L->getHeader() == BB && L->getParentLoop() == 0)
+ printLoop(L);
+ } else {
+ printBasicBlock(BB);
}
-
- // Don't emit prefix or suffix for the terminator...
- visit(*BB->getTerminator());
}
Out << "}\n\n";
}
+void CWriter::printLoop(Loop *L) {
+ Out << " do { /* Syntactic loop '" << L->getHeader()->getName()
+ << "' to make GCC happy */\n";
+ for (unsigned i = 0, e = L->getBlocks().size(); i != e; ++i) {
+ BasicBlock *BB = L->getBlocks()[i];
+ Loop *BBLoop = LI->getLoopFor(BB);
+ if (BBLoop == L)
+ printBasicBlock(BB);
+ else if (BB == BBLoop->getHeader() && BBLoop->getParentLoop() == L)
+ printLoop(BBLoop);
+ }
+ Out << " } while (1); /* end of syntactic loop '"
+ << L->getHeader()->getName() << "' */\n";
+}
+
+void CWriter::printBasicBlock(BasicBlock *BB) {
+
+ // Don't print the label for the basic block if there are no uses, or if
+ // the only terminator use is the predecessor basic block's terminator.
+ // We have to scan the use list because PHI nodes use basic blocks too but
+ // do not require a label to be generated.
+ //
+ bool NeedsLabel = false;
+ for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ if (isGotoCodeNecessary(*PI, BB)) {
+ NeedsLabel = true;
+ break;
+ }
+
+ if (NeedsLabel) Out << Mang->getValueName(BB) << ":\n";
+
+ // Output all of the instructions in the basic block...
+ for (BasicBlock::iterator II = BB->begin(), E = --BB->end(); II != E;
+ ++II) {
+ if (!isInlinableInst(*II) && !isDirectAlloca(II)) {
+ if (II->getType() != Type::VoidTy)
+ outputLValue(II);
+ else
+ Out << " ";
+ visit(*II);
+ Out << ";\n";
+ }
+ }
+
+ // Don't emit prefix or suffix for the terminator...
+ visit(*BB->getTerminator());
+}
+
+
// Specific Instruction type classes... note that all of the casts are
// necessary because we use the instruction classes as opaque types...
//
@@ -1072,22 +1111,18 @@
Out << " }\n";
}
-void CWriter::visitInvokeInst(InvokeInst &II) {
- assert(0 && "Lowerinvoke pass didn't work!");
-}
+bool CWriter::isGotoCodeNecessary(BasicBlock *From, BasicBlock *To) {
+ /// FIXME: This should be reenabled, but loop reordering safe!!
+ return true;
+ if (From->getNext() != To) // Not the direct successor, we need a goto
+ return true;
-void CWriter::visitUnwindInst(UnwindInst &I) {
- assert(0 && "Lowerinvoke pass didn't work!");
-}
+ //isa<SwitchInst>(From->getTerminator())
-static bool isGotoCodeNecessary(BasicBlock *From, BasicBlock *To) {
- // If PHI nodes need copies, we need the copy code...
- if (isa<PHINode>(To->front()) ||
- From->getNext() != To) // Not directly successor, need goto
- return true;
- // Otherwise we don't need the code.
+ if (LI->getLoopFor(From) != LI->getLoopFor(To))
+ return true;
return false;
}
@@ -1108,9 +1143,7 @@
void CWriter::printBranchToBlock(BasicBlock *CurBB, BasicBlock *Succ,
unsigned Indent) {
- if (CurBB->getNext() != Succ ||
- isa<InvokeInst>(CurBB->getTerminator()) ||
- isa<SwitchInst>(CurBB->getTerminator())) {
+ if (isGotoCodeNecessary(CurBB, Succ)) {
Out << std::string(Indent, ' ') << " goto ";
writeOperand(Succ);
Out << ";\n";
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