diff options
Diffstat (limited to 'source')
| -rw-r--r-- | source/slang/diagnostic-defs.h | 5 | ||||
| -rw-r--r-- | source/slang/ir-validate.cpp | 15 | ||||
| -rw-r--r-- | source/slang/lower-to-ir.cpp | 102 |
3 files changed, 110 insertions, 12 deletions
diff --git a/source/slang/diagnostic-defs.h b/source/slang/diagnostic-defs.h index 0dbacafe0..8f564cc59 100644 --- a/source/slang/diagnostic-defs.h +++ b/source/slang/diagnostic-defs.h @@ -303,6 +303,11 @@ DIAGNOSTIC(40006, Error, needCompileTimeConstant, "expected a compile-time const DIAGNOSTIC(40007, Internal, irValidationFailed, "IR validation failed: $0") +// 41000 - IR-level validation issues + +DIAGNOSTIC(41000, Warning, unreachableCode, "unreachable code detected") + + // // 5xxxx - Target code generation. // diff --git a/source/slang/ir-validate.cpp b/source/slang/ir-validate.cpp index 7c04c0873..1f5112a51 100644 --- a/source/slang/ir-validate.cpp +++ b/source/slang/ir-validate.cpp @@ -48,6 +48,21 @@ namespace Slang // Recursively validate the instruction itself. validateIRInst(context, child); + // Do some extra validation around terminator instructions: + // + // * The last instruction of a block should always be a terminator + // * No other instruction should be a terminator + // + if(as<IRBlock>(parent) && (child == parent->getLastChild())) + { + validate(context, as<IRTerminatorInst>(child) != nullptr, child, "last instruction in block must be terminator"); + } + else + { + validate(context, !as<IRTerminatorInst>(child), child, "terminator must be last instruction in a block"); + } + + prevChild = child; } } diff --git a/source/slang/lower-to-ir.cpp b/source/slang/lower-to-ir.cpp index fffd8acf3..371c68809 100644 --- a/source/slang/lower-to-ir.cpp +++ b/source/slang/lower-to-ir.cpp @@ -360,6 +360,11 @@ struct IRGenContext { return shared->compileRequest; } + + DiagnosticSink* getSink() + { + return &getCompileRequest()->mSink; + } }; void setGlobalValue(SharedIRGenContext* sharedContext, Decl* decl, LoweredValInfo value) @@ -2049,9 +2054,35 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> return getBuilder()->createBlock(); } - // Insert a block at the current location (ending - // the previous block with an unconditional jump - // if needed). + /// Does the given block have a terminator? + bool isBlockTerminated(IRBlock* block) + { + return block->getTerminator() != nullptr; + } + + /// Emit a branch to the target block if the current + /// block being inserted into is not already terminated. + void emitBranchIfNeeded(IRBlock* targetBlock) + { + auto builder = getBuilder(); + auto currentBlock = builder->getBlock(); + + // Don't emit if there is no current block. + if(!currentBlock) + return; + + // Don't emit if the block already has a terminator. + if(isBlockTerminated(currentBlock)) + return; + + // The block is unterminated, so cap it off with + // a terminator that branches to the target. + builder->emitBranch(targetBlock); + } + + /// Insert a block at the current location (ending + /// the previous block with an unconditional jump + /// if needed). void insertBlock(IRBlock* block) { auto builder = getBuilder(); @@ -2062,13 +2093,11 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> // If the previous block doesn't already have // a terminator instruction, then be sure to // emit a branch to the new block. - if (prevBlock && !prevBlock->getTerminator()) - { - builder->emitBranch(block); - } + emitBranchIfNeeded(block); + // Add the new block to the function we are building, + // and setit as the block we will be inserting into. parentFunc->addBlock(block); - builder->setInsertInto(block); } @@ -2082,9 +2111,43 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> return block; } + /// Start a new block if there isn't a current + /// block that we can append to. + /// + /// The `stmt` parameter is the statement we + /// are about to emit. + void startBlockIfNeeded(Stmt* stmt) + { + auto builder = getBuilder(); + auto currentBlock = builder->getBlock(); + + // If there is a current block and it hasn't + // been terminated, then we can just use that. + if(currentBlock && !isBlockTerminated(currentBlock)) + { + return; + } + + // We are about to emit code *after* a terminator + // instruction, and there is no label to allow + // branching into this code, so whatever we are + // about to emit is going to be unreachable. + // + // Let's diagnose that here just to help the user. + // + // TODO: We might want to have a more robust check + // for unreachable code based on IR analysis instead, + // at which point we'd probably disable this check. + // + context->getSink()->diagnose(stmt, Diagnostics::unreachableCode); + + startBlock(); + } + void visitIfStmt(IfStmt* stmt) { auto builder = getBuilder(); + startBlockIfNeeded(stmt); auto condExpr = stmt->Predicate; auto thenStmt = stmt->PositiveStatement; @@ -2103,7 +2166,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> insertBlock(thenBlock); lowerStmt(context, thenStmt); - builder->emitBranch(afterBlock); + emitBranchIfNeeded(afterBlock); insertBlock(elseBlock); lowerStmt(context, elseStmt); @@ -2139,6 +2202,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitForStmt(ForStmt* stmt) { auto builder = getBuilder(); + startBlockIfNeeded(stmt); // The initializer clause for the statement // can always safetly be emitted to the current block. @@ -2199,7 +2263,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> } // At the end of the body we need to jump back to the top. - builder->emitBranch(loopHead); + emitBranchIfNeeded(loopHead); // Finally we insert the label that a `break` will jump to insertBlock(breakLabel); @@ -2211,6 +2275,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> // `for` statement, but without a lot of the complications. auto builder = getBuilder(); + startBlockIfNeeded(stmt); // We will create blocks for the various places // we need to jump to inside the control flow, @@ -2260,7 +2325,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> lowerStmt(context, stmt->Statement); // At the end of the body we need to jump back to the top. - builder->emitBranch(loopHead); + emitBranchIfNeeded(loopHead); // Finally we insert the label that a `break` will jump to insertBlock(breakLabel); @@ -2272,6 +2337,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> // `while` statement, just with the test in a different place auto builder = getBuilder(); + startBlockIfNeeded(stmt); // We will create blocks for the various places // we need to jump to inside the control flow, @@ -2328,6 +2394,8 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitExpressionStmt(ExpressionStmt* stmt) { + startBlockIfNeeded(stmt); + // The statement evaluates an expression // (for side effects, one assumes) and then // discards the result. As such, we simply @@ -2343,6 +2411,8 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitDeclStmt(DeclStmt* stmt) { + startBlockIfNeeded(stmt); + // For now, we lower a declaration directly // into the current context. // @@ -2376,6 +2446,8 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitReturnStmt(ReturnStmt* stmt) { + startBlockIfNeeded(stmt); + // A `return` statement turns into a return // instruction. If the statement had an argument // expression, then we need to lower that to @@ -2392,13 +2464,16 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> } } - void visitDiscardStmt(DiscardStmt* /*stmt*/) + void visitDiscardStmt(DiscardStmt* stmt) { + startBlockIfNeeded(stmt); getBuilder()->emitDiscard(); } void visitBreakStmt(BreakStmt* stmt) { + startBlockIfNeeded(stmt); + // Semantic checking is responsible for finding // the statement taht this `break` breaks out of auto parentStmt = stmt->parentStmt; @@ -2415,6 +2490,8 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitContinueStmt(ContinueStmt* stmt) { + startBlockIfNeeded(stmt); + // Semantic checking is responsible for finding // the loop that this `continue` statement continues auto parentStmt = stmt->parentStmt; @@ -2575,6 +2652,7 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor> void visitSwitchStmt(SwitchStmt* stmt) { auto builder = getBuilder(); + startBlockIfNeeded(stmt); // Given a statement: // |