https://github.com/andykaylor created https://github.com/llvm/llvm-project/pull/191029
The CIR popCleanupBlock implementation contained a lot of logic that was copied from the classic codegen implementation but had become effectively dead code after the redesign of cleanup and exception handling in CIR because our cleanups are no longer based on blocks and branches. This change removes that code. >From c9e0d48c2debc8e408d3ae70beea321c0914059c Mon Sep 17 00:00:00 2001 From: Andy Kaylor <[email protected]> Date: Wed, 8 Apr 2026 11:35:55 -0700 Subject: [PATCH] [CIR][NFC] Remove dead code in popCleanupBlock The CIR popCleanupBlock implementation contained a lot of logic that was copied from the classic codegen implementation but had become effectively dead code after the redesign of cleanup and exception handling in CIR because our cleanups are no longer based on blocks and branches. This change removes that code. --- clang/lib/CIR/CodeGen/CIRGenCleanup.cpp | 144 ++---------------------- 1 file changed, 9 insertions(+), 135 deletions(-) diff --git a/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp b/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp index 1bc3df92cc64b..d8d440a60110e 100644 --- a/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp +++ b/clang/lib/CIR/CodeGen/CIRGenCleanup.cpp @@ -300,18 +300,6 @@ static void emitCleanup(CIRGenFunction &cgf, cir::CleanupScopeOp cleanupScope, } } -static mlir::Block *createNormalEntry(CIRGenFunction &cgf, - EHCleanupScope &scope) { - assert(scope.isNormalCleanup()); - mlir::Block *entry = scope.getNormalBlock(); - if (!entry) { - mlir::OpBuilder::InsertionGuard guard(cgf.getBuilder()); - entry = cgf.curLexScope->getOrCreateCleanupBlock(cgf.getBuilder()); - scope.setNormalBlock(entry); - } - return entry; -} - void CIRGenFunction::popCleanupBlock() { assert(!ehStack.empty() && "cleanup stack is empty!"); assert(isa<EHCleanupScope>(*ehStack.begin()) && "top not a cleanup!"); @@ -321,7 +309,6 @@ void CIRGenFunction::popCleanupBlock() { assert(cleanupScope && "CleanupScopeOp is nullptr"); // Remember activation information. - bool isActive = scope.isActive(); Address normalActiveFlag = scope.shouldTestFlagInNormalCleanup() ? scope.getActiveFlag() : Address::invalid(); @@ -329,21 +316,11 @@ void CIRGenFunction::popCleanupBlock() { ? scope.getActiveFlag() : Address::invalid(); - // - whether there's a fallthrough - mlir::Block *fallthroughSource = builder.getInsertionBlock(); - bool hasFallthrough = fallthroughSource != nullptr && isActive; - - bool requiresNormalCleanup = scope.isNormalCleanup() && hasFallthrough; - bool requiresEHCleanup = scope.isEHCleanup() && hasFallthrough; - - // Even if we don't need the normal cleanup, we still need to emit the - // cleanup code if there's an active flag, since the EH path may still - // need to conditionally execute it. - bool hasActiveFlag = normalActiveFlag.isValid() || ehActiveFlag.isValid(); + bool requiresNormalCleanup = scope.isNormalCleanup(); + bool requiresEHCleanup = scope.isEHCleanup(); // If we don't need the cleanup at all, we're done. - assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); - if (!requiresNormalCleanup && !requiresEHCleanup && !hasActiveFlag) { + if (!requiresNormalCleanup && !requiresEHCleanup) { ehStack.popCleanup(); return; } @@ -383,115 +360,12 @@ void CIRGenFunction::popCleanupBlock() { : ehActiveFlag.isValid() ? ehActiveFlag : Address::invalid(); - // If we have a fallthrough and no other need for the cleanup, - // emit it directly. - if (hasFallthrough) { - assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); - ehStack.popCleanup(); - scope.markEmitted(); - emitCleanup(*this, cleanupScope, cleanup, cleanupFlags, cleanupActiveFlag); - } else if (!requiresNormalCleanup && !requiresEHCleanup) { - // The cleanup is inactive but has an active flag. We still need to emit - // the cleanup handler guarded by the flag, since the EH path may need it. - ehStack.popCleanup(); - scope.markEmitted(); - emitCleanup(*this, cleanupScope, cleanup, cleanupFlags, cleanupActiveFlag); - } else { - // Otherwise, the best approach is to thread everything through - // the cleanup block and then try to clean up after ourselves. - - // Force the entry block to exist. - mlir::Block *normalEntry = createNormalEntry(*this, scope); - - // I. Set up the fallthrough edge in. - mlir::OpBuilder::InsertPoint savedInactiveFallthroughIP; - - // If we have a fallthrough source, but this cleanup is inactive, - // save and clear the IP. - if (!hasFallthrough && fallthroughSource) { - assert(!isActive && "source without fallthrough for active cleanup"); - savedInactiveFallthroughIP = builder.saveInsertionPoint(); - } - - // II. Emit the entry block. This implicitly branches to it if - // we have fallthrough. All the fixups and existing branches - // should already be branched to it. - builder.setInsertionPointToEnd(normalEntry); - - // intercept normal cleanup to mark SEH scope end - assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); - - // III. Figure out where we're going and build the cleanup - // epilogue. - bool hasEnclosingCleanups = - (scope.getEnclosingNormalCleanup() != ehStack.stable_end()); - - // Compute the branch-through dest if we need it: - // - if there are branch-throughs threaded through the scope - // - if fall-through is a branch-through - // - if there are fixups that will be optimistically forwarded - // to the enclosing cleanup - assert(!cir::MissingFeatures::cleanupBranchThrough()); - if (hasEnclosingCleanups) - cgm.errorNYI("cleanup branch-through dest"); - - mlir::Block *fallthroughDest = nullptr; - - // If there's exactly one branch-after and no other threads, - // we can route it without a switch. - // Skip for SEH, since ExitSwitch is used to generate code to indicate - // abnormal termination. (SEH: Except _leave and fall-through at - // the end, all other exits in a _try (return/goto/continue/break) - // are considered as abnormal terminations, using NormalCleanupDestSlot - // to indicate abnormal termination) - assert(!cir::MissingFeatures::cleanupBranchThrough()); - assert(!cir::MissingFeatures::ehCleanupScopeRequiresEHCleanup()); - - // IV. Pop the cleanup and emit it. - scope.markEmitted(); - ehStack.popCleanup(); - assert(ehStack.hasNormalCleanups() == hasEnclosingCleanups); - emitCleanup(*this, cleanupScope, cleanup, cleanupFlags, cleanupActiveFlag); - - // Append the prepared cleanup prologue from above. - assert(!cir::MissingFeatures::cleanupAppendInsts()); - - // V. Set up the fallthrough edge out. - - // Case 1: a fallthrough source exists but doesn't branch to the - // cleanup because the cleanup is inactive. - if (!hasFallthrough && fallthroughSource) { - // Prebranched fallthrough was forwarded earlier. - // Non-prebranched fallthrough doesn't need to be forwarded. - // Either way, all we need to do is restore the IP we cleared before. - assert(!isActive); - cgm.errorNYI("cleanup inactive fallthrough"); - - // Case 2: a fallthrough source exists and should branch to the - // cleanup, but we're not supposed to branch through to the next - // cleanup. - } else if (hasFallthrough && fallthroughDest) { - cgm.errorNYI("cleanup fallthrough destination"); - - // Case 3: a fallthrough source exists and should branch to the - // cleanup and then through to the next. - } else if (hasFallthrough) { - // Everything is already set up for this. - - // Case 4: no fallthrough source exists. - } else { - // FIXME(cir): should we clear insertion point here? - } - - // VI. Assorted cleaning. - - // Check whether we can merge NormalEntry into a single predecessor. - // This might invalidate (non-IR) pointers to NormalEntry. - // - // If it did invalidate those pointers, and normalEntry was the same - // as NormalExit, go back and patch up the fixups. - assert(!cir::MissingFeatures::simplifyCleanupEntry()); - } + // In CIR, the cleanup code is emitted into the cleanup region of the + // cir.cleanup.scope op. There is no CFG threading needed — the FlattenCFG + // pass handles lowering the structured cleanup scope. + ehStack.popCleanup(); + scope.markEmitted(); + emitCleanup(*this, cleanupScope, cleanup, cleanupFlags, cleanupActiveFlag); } /// Pops cleanup blocks until the given savepoint is reached. _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
