diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp --- a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp +++ b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp @@ -670,9 +670,27 @@ MachineBasicBlock *EHPadLayoutPred = MBB.getPrevNode(); MachineBasicBlock *Cont = BeginToEnd[EHPadToTry[&MBB]]->getParent(); bool Analyzable = !TII.analyzeBranch(*EHPadLayoutPred, TBB, FBB, Cond); + // This condition means either + // 1. This BB ends with a single unconditional branch whose destinaion is + // Cont. + // 2. This BB ends with a conditional branch followed by an unconditional + // branch, and the unconditional branch's destination is Cont. + // In both cases, we want to remove the last (= unconditional) branch. if (Analyzable && ((Cond.empty() && TBB && TBB == Cont) || - (!Cond.empty() && FBB && FBB == Cont))) - TII.removeBranch(*EHPadLayoutPred); + (!Cond.empty() && FBB && FBB == Cont))) { + bool ErasedUncondBr = false; + for (auto I = EHPadLayoutPred->end(), E = EHPadLayoutPred->begin(); + I != E; --I) { + auto PrevI = std::prev(I); + if (PrevI->isTerminator()) { + assert(PrevI->getOpcode() == WebAssembly::BR); + PrevI->eraseFromParent(); + ErasedUncondBr = true; + break; + } + } + assert(ErasedUncondBr && "Unconditional branch not erased!"); + } } // When there are block / end_block markers that overlap with try / end_try diff --git a/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll b/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll --- a/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll +++ b/llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll @@ -1,5 +1,6 @@ ; REQUIRES: asserts ; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling | FileCheck %s +; RUN: llc < %s -disable-wasm-fallthrough-return-opt -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling ; RUN: llc < %s -O0 -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -verify-machineinstrs -exception-model=wasm -mattr=+exception-handling | FileCheck %s --check-prefix=NOOPT ; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling -wasm-disable-ehpad-sort | FileCheck %s --check-prefix=NOSORT ; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-disable-explicit-locals -wasm-keep-registers -disable-block-placement -verify-machineinstrs -fast-isel=false -machine-sink-split-probability-threshold=0 -cgp-freq-ratio-to-skip-merge=1000 -exception-model=wasm -mattr=+exception-handling -wasm-disable-ehpad-sort -stats 2>&1 | FileCheck %s --check-prefix=NOSORT-STAT @@ -856,11 +857,11 @@ entry: br label %loop -loop: +loop: ; preds = %try.cont, %entry invoke void @foo() to label %bb0 unwind label %catch.dispatch0 -bb0: +bb0: ; preds = %loop %cmp = icmp ne i32 %a, %b br i1 %cmp, label %bb1, label %last @@ -886,10 +887,50 @@ %7 = call i32 @llvm.wasm.get.ehselector(token %5) catchret from %5 to label %try.cont -try.cont: ; preds = %catch.start, %loop +try.cont: ; preds = %catch.start1, %catch.start0, %bb1 br label %loop -last: +last: ; preds = %bb0 + ret void +} + +; Tests if CFGStackify's removeUnnecessaryInstrs() removes unnecessary branches +; correctly. +; CHECK-LABEL: test17 +define void @test17(i32 %n) personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) { +entry: + invoke void @foo() + to label %for.body unwind label %catch.dispatch + +for.body: ; preds = %for.end, %entry + %i = phi i32 [ %inc, %for.end ], [ 0, %entry ] + invoke void @foo() + to label %for.end unwind label %catch.dispatch + +; Before going to CFGStackify, this BB will have a conditional branch followed +; by an unconditional branch. CFGStackify should remove only the unconditional +; one. +for.end: ; preds = %for.body + %inc = add nuw nsw i32 %i, 1 + %exitcond = icmp eq i32 %inc, %n + br i1 %exitcond, label %try.cont, label %for.body +; CHECK: br_if +; CHECK-NOT: br +; CHECK: end_loop +; CHECK: catch + +catch.dispatch: ; preds = %for.body, %entry + %0 = catchswitch within none [label %catch.start] unwind to caller + +catch.start: ; preds = %catch.dispatch + %1 = catchpad within %0 [i8* null] + %2 = call i8* @llvm.wasm.get.exception(token %1) + %3 = call i32 @llvm.wasm.get.ehselector(token %1) + %4 = call i8* @__cxa_begin_catch(i8* %2) #2 [ "funclet"(token %1) ] + call void @__cxa_end_catch() [ "funclet"(token %1) ] + catchret from %1 to label %try.cont + +try.cont: ; preds = %catch.start, %for.end ret void }