Move EmitBranchOnBoolExpr and ConstantFoldsToSimpleInteger to
CodeGenFunction.cpp. Change VisitConditionalOperator to use
constant fold instead of codegen'ing a constant conditional.
Change ForStmt to use EmitBranchOnBoolExpr, this shrinks
expr.c very slightly to 40239 lines.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59113 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index d5e8c8a..a797d75 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -15,6 +15,7 @@
#include "CodeGenModule.h"
#include "CGDebugInfo.h"
#include "clang/Basic/TargetInfo.h"
+#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "llvm/Support/CFG.h"
@@ -186,6 +187,90 @@
return false;
}
+
+/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to
+/// a constant, or if it does but contains a label, return 0. If it constant
+/// folds to 'true' and does not contain a label, return 1, if it constant folds
+/// to 'false' and does not contain a label, return -1.
+int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) {
+ APValue V;
+ if (!Cond->tryEvaluate(V, getContext()))
+ return 0; // Not foldable.
+
+ if (CodeGenFunction::ContainsLabel(Cond))
+ return 0; // Contains a label.
+
+ return V.getInt().getBoolValue() ? 1 : -1;
+}
+
+
+/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
+/// statement) to the specified blocks. Based on the condition, this might try
+/// to simplify the codegen of the conditional based on the branch.
+///
+void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
+ llvm::BasicBlock *TrueBlock,
+ llvm::BasicBlock *FalseBlock) {
+ if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond))
+ return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock);
+
+ if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
+ // Handle X && Y in a condition.
+ if (CondBOp->getOpcode() == BinaryOperator::LAnd) {
+ // If we have "1 && X", simplify the code. "0 && X" would have constant
+ // folded if the case was simple enough.
+ if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) {
+ // br(1 && X) -> br(X).
+ return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
+ }
+
+ // If we have "X && 1", simplify the code to use an uncond branch.
+ // "X && 0" would have been constant folded to 0.
+ if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) {
+ // br(X && 1) -> br(X).
+ return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
+ }
+
+ // Emit the LHS as a conditional. If the LHS conditional is false, we
+ // want to jump to the FalseBlock.
+ llvm::BasicBlock *LHSTrue = createBasicBlock("land_lhs_true");
+ EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
+ EmitBlock(LHSTrue);
+
+ EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
+ return;
+ } else if (CondBOp->getOpcode() == BinaryOperator::LOr) {
+ // If we have "0 || X", simplify the code. "1 || X" would have constant
+ // folded if the case was simple enough.
+ if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) {
+ // br(0 || X) -> br(X).
+ return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
+ }
+
+ // If we have "X || 0", simplify the code to use an uncond branch.
+ // "X || 1" would have been constant folded to 1.
+ if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) {
+ // br(X || 0) -> br(X).
+ return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
+ }
+
+ // Emit the LHS as a conditional. If the LHS conditional is true, we
+ // want to jump to the TrueBlock.
+ llvm::BasicBlock *LHSFalse = createBasicBlock("lor_lhs_false");
+ EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
+ EmitBlock(LHSFalse);
+
+ EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
+ return;
+ }
+
+ }
+
+ // Emit the code with the fully general case.
+ llvm::Value *CondV = EvaluateExprAsBool(Cond);
+ Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
+}
+
/// getCGRecordLayout - Return record layout info.
const CGRecordLayout *CodeGenFunction::getCGRecordLayout(CodeGenTypes &CGT,
QualType Ty) {