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Merged
isuckatcs merged 1 commit into from
Mar 3, 2025
Merged

[Codegen] do not emit duplicate br instructions #6

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1 change: 1 addition & 0 deletions include/codegen.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,7 @@ class Codegen {
llvm::Value *storeValue(llvm::Value *val, llvm::Value *ptr, const Type &type);
llvm::Value *doubleToBool(llvm::Value *v);
llvm::Value *boolToDouble(llvm::Value *v);
void breakIntoBB(llvm::BasicBlock *targetBB);

llvm::Function *getCurrentFunction();
llvm::AllocaInst *allocateStackVariable(const std::string_view identifier,
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35 changes: 21 additions & 14 deletions src/codegen.cpp
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Expand Up @@ -62,14 +62,13 @@ llvm::Value *Codegen::generateIfStmt(const ResolvedIfStmt &stmt) {
trueBB->insertInto(function);
builder.SetInsertPoint(trueBB);
generateBlock(*stmt.trueBlock);
builder.CreateBr(exitBB);
breakIntoBB(exitBB);

if (stmt.falseBlock) {
elseBB->insertInto(function);

builder.SetInsertPoint(elseBB);
generateBlock(*stmt.falseBlock);
builder.CreateBr(exitBB);
breakIntoBB(exitBB);
}

exitBB->insertInto(function);
Expand All @@ -92,7 +91,7 @@ llvm::Value *Codegen::generateWhileStmt(const ResolvedWhileStmt &stmt) {

builder.SetInsertPoint(body);
generateBlock(*stmt.body);
builder.CreateBr(header);
breakIntoBB(header);

builder.SetInsertPoint(exit);
return nullptr;
Expand Down Expand Up @@ -120,7 +119,8 @@ llvm::Value *Codegen::generateReturnStmt(const ResolvedReturnStmt &stmt) {
storeValue(generateExpr(*stmt.expr), retVal, stmt.expr->type);

assert(retBB && "function with return stmt doesn't have a return block");
return builder.CreateBr(retBB);
breakIntoBB(retBB);
return nullptr;
}

llvm::Value *Codegen::generateMemberExpr(const ResolvedMemberExpr &memberExpr,
Expand Down Expand Up @@ -290,6 +290,9 @@ Codegen::generateBinaryOperator(const ResolvedBinaryOperator &binop) {

builder.SetInsertPoint(rhsBB);
llvm::Value *rhs = doubleToBool(generateExpr(*binop.rhs));

assert(!builder.GetInsertBlock()->getTerminator() &&
"a binop terminated the current block");
builder.CreateBr(mergeBB);

rhsBB = builder.GetInsertBlock();
Expand Down Expand Up @@ -362,6 +365,15 @@ llvm::Value *Codegen::boolToDouble(llvm::Value *v) {
return builder.CreateUIToFP(v, builder.getDoubleTy(), "to.double");
}

void Codegen::breakIntoBB(llvm::BasicBlock *targetBB) {
llvm::BasicBlock *currentBB = builder.GetInsertBlock();

if (currentBB && !currentBB->getTerminator())
builder.CreateBr(targetBB);

builder.ClearInsertionPoint();
}

llvm::Function *Codegen::getCurrentFunction() {
return builder.GetInsertBlock()->getParent();
};
Expand Down Expand Up @@ -405,15 +417,10 @@ void Codegen::generateBlock(const ResolvedBlock &block) {
for (auto &&stmt : block.statements) {
generateStmt(*stmt);

// After a return statement we clear the insertion point, so that
// no other instructions are inserted into the current block and break.
// The break ensures that no other instruction is generated that will be
// inserted regardless of there is no insertion point and crash (e.g.:
// CreateStore, CreateLoad).
if (dynamic_cast<const ResolvedReturnStmt *>(stmt.get())) {
builder.ClearInsertionPoint();
// We exited the current basic block for some reason, so there is
// no need for generating the remaining instructions.
if (!builder.GetInsertBlock())
break;
}
}
}

Expand Down Expand Up @@ -460,7 +467,7 @@ void Codegen::generateFunctionBody(const ResolvedFunctionDecl &functionDecl) {
generateBlock(*functionDecl.body);

if (retBB->hasNPredecessorsOrMore(1)) {
builder.CreateBr(retBB);
breakIntoBB(retBB);
retBB->insertInto(function);
builder.SetInsertPoint(retBB);
}
Expand Down
2 changes: 1 addition & 1 deletion test/codegen/condition_empty_merge.yl
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Expand Up @@ -22,7 +22,7 @@ fn main(): void {
// CHECK-NEXT: if.true: ; preds = %entry
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: if.exit: ; preds = <null operand!>, %entry
// CHECK-NEXT: if.exit: ; preds = %entry
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = %if.exit, %if.true
Expand Down
4 changes: 2 additions & 2 deletions test/codegen/constexpr.yl
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Expand Up @@ -14,7 +14,7 @@ fn constant(): number {
// CHECK-NEXT: store double 1.000000e+00, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: %0 = load double, double* %retval, align 8
// CHECK-NEXT: ret double %0
// CHECK-NEXT: }
Expand All @@ -28,7 +28,7 @@ fn constant2(): number {
// CHECK-NEXT: store double 0.000000e+00, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: %0 = load double, double* %retval, align 8
// CHECK-NEXT: ret double %0
// CHECK-NEXT: }
Expand Down
2 changes: 1 addition & 1 deletion test/codegen/exercise/immutable_parameters.yl
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Expand Up @@ -18,7 +18,7 @@ fn foo(s: S, y: number): number {
// CHECK-NEXT: store double %3, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: %4 = load double, double* %retval, align 8
// CHECK-NEXT: ret double %4
// CHECK-NEXT: }
Expand Down
4 changes: 2 additions & 2 deletions test/codegen/exercise/return_struct.yl
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Expand Up @@ -44,7 +44,7 @@ fn foo(var x: number): Small {
// CHECK-NEXT: br label %return

// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }

Expand Down Expand Up @@ -74,7 +74,7 @@ fn bar(): S {

// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }

Expand Down
2 changes: 1 addition & 1 deletion test/codegen/exercise/struct_parameter.yl
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Expand Up @@ -30,7 +30,7 @@ fn bar(var s: S): S {
// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %0, i8* align 8 %1, i64 16, i1 false)
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }

Expand Down
2 changes: 1 addition & 1 deletion test/codegen/exercise/structs_generated_first.yl
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Expand Up @@ -25,7 +25,7 @@ fn foo(s: S): S2 {

// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }

Expand Down
2 changes: 1 addition & 1 deletion test/codegen/multiple_return.yl
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Expand Up @@ -10,6 +10,6 @@ fn main(): void {
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }
6 changes: 3 additions & 3 deletions test/codegen/multiple_return_if.yl
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Expand Up @@ -39,14 +39,14 @@ fn foo(var x: number): number {
// CHECK-NEXT: store double 1.000000e+01, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: if.exit: ; preds = <null operand!>, %if.false
// CHECK-NEXT: if.exit: ; preds = %if.false
// CHECK-NEXT: br label %if.exit5
// CHECK-NEXT:
// CHECK-NEXT: if.exit5: ; preds = %if.exit, <null operand!>
// CHECK-NEXT: if.exit5: ; preds = %if.exit
// CHECK-NEXT: store double 5.200000e+00, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %if.exit5, %if.true4, %if.true
// CHECK-NEXT: return: ; preds = %if.exit5, %if.true4, %if.true
// CHECK-NEXT: %4 = load double, double* %retval, align 8
// CHECK-NEXT: ret double %4
// CHECK-NEXT: }
Expand Down
4 changes: 2 additions & 2 deletions test/codegen/multiple_return_while.yl
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Expand Up @@ -33,11 +33,11 @@ fn foo(var x: number): number {
// CHECK-NEXT: store double 3.000000e+00, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: if.exit: ; preds = <null operand!>, %while.body
// CHECK-NEXT: if.exit: ; preds = %while.body
// CHECK-NEXT: store double 5.000000e+00, double* %retval, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %while.exit, %if.exit, %if.true
// CHECK-NEXT: return: ; preds = %while.exit, %if.exit, %if.true
// CHECK-NEXT: %7 = load double, double* %retval, align 8
// CHECK-NEXT: ret double %7

Expand Down
10 changes: 5 additions & 5 deletions test/codegen/return.yl
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Expand Up @@ -9,7 +9,7 @@ fn noInsertPoint(): void {
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = <null operand!>, %entry
// CHECK-NEXT: return: ; preds = %entry
// CHECK-NEXT: ret void
// CHECK-NEXT: }

Expand All @@ -25,7 +25,7 @@ fn insertPointEmptyBlock(): void {
// CHECK-NEXT: if.true: ; preds = %entry
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: if.exit: ; preds = <null operand!>, %entry
// CHECK-NEXT: if.exit: ; preds = %entry
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: return: ; preds = %if.exit, %if.true
Expand All @@ -41,7 +41,7 @@ fn insertPointEmptyBlock2(): void {
// CHECK-NEXT: entry:
// CHECK-NEXT: br label %while.cond
// CHECK-NEXT:
// CHECK-NEXT: while.cond: ; preds = <null operand!>, %entry
// CHECK-NEXT: while.cond: ; preds = %entry
// CHECK-NEXT: br i1 true, label %while.body, label %while.exit
// CHECK-NEXT:
// CHECK-NEXT: while.body: ; preds = %while.cond
Expand Down Expand Up @@ -69,7 +69,7 @@ fn insertPointNonEmptyBlock(): void {
// CHECK-NEXT: if.true: ; preds = %entry
// CHECK-NEXT: br label %return
// CHECK-NEXT:
// CHECK-NEXT: if.exit: ; preds = <null operand!>, %entry
// CHECK-NEXT: if.exit: ; preds = %entry
// CHECK-NEXT: store double 1.000000e+00, double* %x, align 8
// CHECK-NEXT: br label %return
// CHECK-NEXT:
Expand All @@ -89,7 +89,7 @@ fn insertPointNonEmptyBlock2(): void {
// CHECK-NEXT: %x = alloca double, align 8
// CHECK-NEXT: br label %while.cond
// CHECK-NEXT:
// CHECK-NEXT: while.cond: ; preds = <null operand!>, %entry
// CHECK-NEXT: while.cond: ; preds = %entry
// CHECK-NEXT: br i1 true, label %while.body, label %while.exit
// CHECK-NEXT:
// CHECK-NEXT: while.body: ; preds = %while.cond
Expand Down
2 changes: 1 addition & 1 deletion test/codegen/while_empty_exit.yl
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Expand Up @@ -11,7 +11,7 @@ fn foo(var x: number): void {
// CHECK-NEXT: store double %x, double* %x1, align 8
// CHECK-NEXT: br label %while.cond
// CHECK-NEXT:
// CHECK-NEXT: while.cond: ; preds = <null operand!>, %entry
// CHECK-NEXT: while.cond: ; preds = %entry
// CHECK-NEXT: %0 = load double, double* %x1, align 8
// CHECK-NEXT: %1 = fcmp ogt double %0, 1.000000e+00
// CHECK-NEXT: %to.double = uitofp i1 %1 to double
Expand Down