[llvm-commits] CVS: llvm/lib/CodeGen/PreOpts/PreSelection.cpp
Vikram Adve
vadve at cs.uiuc.edu
Sat Oct 12 19:03:01 PDT 2002
Changes in directory llvm/lib/CodeGen/PreOpts:
PreSelection.cpp updated: 1.2 -> 1.3
---
Log message:
Major fix: extract ConstantExpr nodes and decompose them into symbolic
instructions so that (a) constant folding is done automatically before
code generation, and (b) selection does not have to deal with them.
Also, check for ConstantPointerRefs in additional to GlobalValues
when creating a GEP to load a global address.
---
Diffs of the changes:
Index: llvm/lib/CodeGen/PreOpts/PreSelection.cpp
diff -u llvm/lib/CodeGen/PreOpts/PreSelection.cpp:1.2 llvm/lib/CodeGen/PreOpts/PreSelection.cpp:1.3
--- llvm/lib/CodeGen/PreOpts/PreSelection.cpp:1.2 Fri Sep 27 09:24:45 2002
+++ llvm/lib/CodeGen/PreOpts/PreSelection.cpp Sat Oct 12 19:01:57 2002
@@ -23,8 +23,8 @@
#include "llvm/Annotation.h"
#include "Support/CommandLine.h"
#include "Support/NonCopyable.h"
-using std::map;
-using std::cerr;
+#include <algorithm>
+using namespace std;
namespace {
//===--------------------------------------------------------------------===//
@@ -51,7 +51,7 @@
// The pool of constants that must be emitted for a module.
// This is a single pool for the entire module and is shared by
// all invocations of the PreSelection pass for this module by putting
- // this as as annotation on the Module object.
+ // this as an annotation on the Module object.
// A single GlobalVariable is created for each constant in the pool
// representing the memory for that constant.
//
@@ -118,8 +118,6 @@
const TargetMachine ⌖
Function* function;
- GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction* insertBefore = 0);
-
GlobalVariable* getGlobalForConstant(Constant* CV) {
Module* M = function->getParent();
return ConstantPoolForModule::get(M).getGlobalForConstant(CV);
@@ -162,18 +160,76 @@
"Specialize LLVM code for a target machine",
createPreSelectionPass);
-// PreSelection::getGlobalAddr: Put address of a global into a v. register.
-GetElementPtrInst*
-PreSelection::getGlobalAddr(Value* ptr, Instruction* insertBefore)
+//------------------------------------------------------------------------------
+// Helper functions used by methods of class PreSelection
+//------------------------------------------------------------------------------
+
+
+// getGlobalAddr(): Put address of a global into a v. register.
+static GetElementPtrInst* getGlobalAddr(Value* ptr, Instruction& insertBefore)
{
+ if (isa<ConstantPointerRef>(ptr))
+ ptr = cast<ConstantPointerRef>(ptr)->getValue();
+
return (isa<GlobalValue>(ptr))
? new GetElementPtrInst(ptr,
std::vector<Value*>(1, ConstantSInt::get(Type::LongTy, 0U)),
- "addrOfGlobal", insertBefore)
+ "addrOfGlobal", &insertBefore)
: NULL;
}
+// Wrapper on Constant::classof to use in find_if :-(
+inline static bool nonConstant(const Use& U)
+{
+ return ! isa<Constant>(U);
+}
+
+
+static Instruction* DecomposeConstantExpr(ConstantExpr* CE,
+ Instruction& insertBefore)
+{
+ Value *getArg1, *getArg2;
+
+ switch(CE->getOpcode())
+ {
+ case Instruction::Cast:
+ getArg1 = CE->getOperand(0);
+ if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
+ getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
+ return new CastInst(getArg1, CE->getType(), "constantCast",&insertBefore);
+
+ case Instruction::GetElementPtr:
+# ifndef NDEBUG
+ assert(find_if(++CE->op_begin(), CE->op_end(),nonConstant) == CE->op_end()
+ && "All indices in ConstantExpr getelementptr must be constant!");
+# endif
+ getArg1 = CE->getOperand(0);
+ if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
+ getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
+ else if (GetElementPtrInst* gep = getGlobalAddr(getArg1, insertBefore))
+ getArg1 = gep;
+ return new GetElementPtrInst(getArg1,
+ std::vector<Value*>(++CE->op_begin(), CE->op_end()),
+ "constantGEP", &insertBefore);
+
+ default: // must be a binary operator
+ assert(CE->getOpcode() >= Instruction::FirstBinaryOp &&
+ CE->getOpcode() < Instruction::NumBinaryOps &&
+ "Unrecognized opcode in ConstantExpr");
+ getArg1 = CE->getOperand(0);
+ if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg1))
+ getArg1 = DecomposeConstantExpr(CEarg, insertBefore);
+ getArg2 = CE->getOperand(1);
+ if (ConstantExpr* CEarg = dyn_cast<ConstantExpr>(getArg2))
+ getArg2 = DecomposeConstantExpr(CEarg, insertBefore);
+ return BinaryOperator::create((Instruction::BinaryOps) CE->getOpcode(),
+ getArg1, getArg2,
+ "constantBinaryOp", &insertBefore);
+ }
+}
+
+
//------------------------------------------------------------------------------
// Instruction visitor methods to perform instruction-specific operations
//------------------------------------------------------------------------------
@@ -192,7 +248,7 @@
PreSelection::visitGetElementPtrInst(GetElementPtrInst &I)
{
// Check for a global and put its address into a register before this instr
- if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), &I))
+ if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
// Decompose multidimensional array references
@@ -208,7 +264,7 @@
PreSelection::visitLoadInst(LoadInst &I)
{
// Check for a global and put its address into a register before this instr
- if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), &I))
+ if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
// Perform other transformations common to all instructions
@@ -221,7 +277,7 @@
PreSelection::visitStoreInst(StoreInst &I)
{
// Check for a global and put its address into a register before this instr
- if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), &I))
+ if (GetElementPtrInst* gep = getGlobalAddr(I.getPointerOperand(), I))
I.setOperand(I.getPointerOperandIndex(), gep); // replace pointer operand
// Perform other transformations common to all instructions
@@ -229,12 +285,14 @@
}
-// Cast instructions: make multi-step casts explicit
-// -- float/double to uint32_t:
-// If target does not have a float-to-unsigned instruction, we
-// need to convert to uint64_t and then to uint32_t, or we may
-// overflow the signed int representation for legal uint32_t
-// values. Expand this without checking target.
+// Cast instructions:
+// -- check if argument is a global
+// -- make multi-step casts explicit:
+// -- float/double to uint32_t:
+// If target does not have a float-to-unsigned instruction, we
+// need to convert to uint64_t and then to uint32_t, or we may
+// overflow the signed int representation for legal uint32_t
+// values. Expand this without checking target.
//
void
PreSelection::visitCastInst(CastInst &I)
@@ -242,8 +300,12 @@
CastInst* castI = NULL;
// Check for a global and put its address into a register before this instr
- if (I.getType() == Type::UIntTy &&
- I.getOperand(0)->getType()->isFloatingPoint())
+ if (GetElementPtrInst* gep = getGlobalAddr(I.getOperand(0), I))
+ {
+ I.setOperand(0, gep); // replace pointer operand
+ }
+ else if (I.getType() == Type::UIntTy &&
+ I.getOperand(0)->getType()->isFloatingPoint())
{ // insert a cast-fp-to-long before I, and then replace the operand of I
castI = new CastInst(I.getOperand(0), Type::LongTy, "fp2Long2Uint", &I);
I.setOperand(0, castI); // replace fp operand with long
@@ -287,10 +349,15 @@
PreSelection::visitOneOperand(Instruction &I, Constant* CV, unsigned opNum,
Instruction& insertBefore)
{
- if (target.getInstrInfo().ConstantTypeMustBeLoaded(CV))
+ if (ConstantExpr* CE = dyn_cast<ConstantExpr>(CV))
+ { // load-time constant: factor it out so we optimize as best we can
+ Instruction* computeConst = DecomposeConstantExpr(CE, insertBefore);
+ I.setOperand(opNum, computeConst); // replace expr operand with result
+ }
+ else if (target.getInstrInfo().ConstantTypeMustBeLoaded(CV))
{ // load address of constant into a register, then load the constant
GetElementPtrInst* gep = getGlobalAddr(getGlobalForConstant(CV),
- &insertBefore);
+ insertBefore);
LoadInst* ldI = new LoadInst(gep, "loadConst", &insertBefore);
I.setOperand(opNum, ldI); // replace operand with copy in v.reg.
}
@@ -301,6 +368,7 @@
I.setOperand(opNum, castI); // replace operand with copy in v.reg.
}
}
+
//===----------------------------------------------------------------------===//
// createPreSelectionPass - Public entrypoint for pre-selection pass
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