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emit better codegen for ||/&&, shrinking expr.ll by another 240 lines. 

This happens for stuff like this:

x = cond1 || cond2 || cond3 || cond4;

llvm-svn: 59123
This commit is contained in:
Chris Lattner 2008-11-12 08:38:24 +00:00
parent 2907b0085c
commit 35710d18fe
1 changed files with 31 additions and 19 deletions
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48
clang/lib/CodeGen/CGExprScalar.cpp
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@ -22,6 +22,7 @@
#include "llvm/GlobalVariable.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/CFG.h"
#include <cstdarg>
using namespace clang;
@ -1035,22 +1036,27 @@ Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land_cont");
llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("land_rhs");
Value *LHSCond = CGF.EvaluateExprAsBool(E->getLHS());
Builder.CreateCondBr(LHSCond, RHSBlock, ContBlock);
llvm::BasicBlock *OrigBlock = Builder.GetInsertBlock();
// Branch on the LHS first. If it is false, go to the failure (cont) block.
CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
// Any edges into the ContBlock are now from an (indeterminate number of)
// edges from this first condition. All of these values will be false. Start
// setting up the PHI node in the Cont Block for this.
llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
PN->reserveOperandSpace(2); // Normal case, two inputs.
for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
PI != PE; ++PI)
PN->addIncoming(llvm::ConstantInt::getFalse(), *PI);
CGF.EmitBlock(RHSBlock);
Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
// Reaquire the RHS block, as there may be subblocks inserted.
RHSBlock = Builder.GetInsertBlock();
CGF.EmitBlock(ContBlock);
// Create a PHI node. If we just evaluted the LHS condition, the result is
// false. If we evaluated both, the result is the RHS condition.
llvm::PHINode *PN = Builder.CreatePHI(llvm::Type::Int1Ty, "land");
PN->reserveOperandSpace(2);
PN->addIncoming(llvm::ConstantInt::getFalse(), OrigBlock);
// Emit an unconditional branch from this block to ContBlock. Insert an entry
// into the phi node for the edge with the value of RHSCond.
CGF.EmitBlock(ContBlock);
PN->addIncoming(RHSCond, RHSBlock);
// ZExt result to int.
@ -1075,22 +1081,28 @@ Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor_cont");
llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor_rhs");
Value *LHSCond = CGF.EvaluateExprAsBool(E->getLHS());
Builder.CreateCondBr(LHSCond, ContBlock, RHSBlock);
llvm::BasicBlock *OrigBlock = Builder.GetInsertBlock();
// Branch on the LHS first. If it is true, go to the success (cont) block.
CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
// Any edges into the ContBlock are now from an (indeterminate number of)
// edges from this first condition. All of these values will be true. Start
// setting up the PHI node in the Cont Block for this.
llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
PN->reserveOperandSpace(2); // Normal case, two inputs.
for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
PI != PE; ++PI)
PN->addIncoming(llvm::ConstantInt::getTrue(), *PI);
// Emit the RHS condition as a bool value.
CGF.EmitBlock(RHSBlock);
Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
// Reaquire the RHS block, as there may be subblocks inserted.
RHSBlock = Builder.GetInsertBlock();
CGF.EmitBlock(ContBlock);
// Create a PHI node. If we just evaluted the LHS condition, the result is
// true. If we evaluated both, the result is the RHS condition.
llvm::PHINode *PN = Builder.CreatePHI(llvm::Type::Int1Ty, "lor");
PN->reserveOperandSpace(2);
PN->addIncoming(llvm::ConstantInt::getTrue(), OrigBlock);
// Emit an unconditional branch from this block to ContBlock. Insert an entry
// into the phi node for the edge with the value of RHSCond.
CGF.EmitBlock(ContBlock);
PN->addIncoming(RHSCond, RHSBlock);
// ZExt result to int.