diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h --- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h +++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.h @@ -26,7 +26,7 @@ class WebAssemblyInstPrinter final : public MCInstPrinter { uint64_t ControlFlowCounter = 0; SmallVector, 4> ControlFlowStack; - SmallVector EHPadStack; + SmallVector TryStack; enum EHInstKind { TRY, CATCH, CATCH_ALL }; SmallVector EHInstStack; diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp --- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp +++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp @@ -104,7 +104,7 @@ case WebAssembly::TRY: case WebAssembly::TRY_S: ControlFlowStack.push_back(std::make_pair(ControlFlowCounter, false)); - EHPadStack.push_back(ControlFlowCounter++); + TryStack.push_back(ControlFlowCounter++); EHInstStack.push_back(TRY); return; @@ -149,11 +149,10 @@ } else if (EHInstStack.back() == CATCH_ALL) { printAnnotation(OS, "catch/catch_all cannot occur after catch_all"); } else if (EHInstStack.back() == TRY) { - if (EHPadStack.empty()) { + if (TryStack.empty()) { printAnnotation(OS, "try-catch mismatch!"); } else { - printAnnotation(OS, - "catch" + utostr(EHPadStack.pop_back_val()) + ':'); + printAnnotation(OS, "catch" + utostr(TryStack.pop_back_val()) + ':'); } EHInstStack.pop_back(); if (Opc == WebAssembly::CATCH || Opc == WebAssembly::CATCH_S) { @@ -168,28 +167,27 @@ case WebAssembly::RETHROW_S: // 'rethrow' rethrows to the nearest enclosing catch scope, if any. If // there's no enclosing catch scope, it throws up to the caller. - if (EHPadStack.empty()) { + if (TryStack.empty()) { printAnnotation(OS, "to caller"); } else { - printAnnotation(OS, "down to catch" + utostr(EHPadStack.back())); + printAnnotation(OS, "down to catch" + utostr(TryStack.back())); } return; case WebAssembly::DELEGATE: case WebAssembly::DELEGATE_S: - if (ControlFlowStack.empty() || EHPadStack.empty() || - EHInstStack.empty()) { + if (ControlFlowStack.empty() || TryStack.empty() || EHInstStack.empty()) { printAnnotation(OS, "try-delegate mismatch!"); } else { // 'delegate' is // 1. A marker for the end of block label // 2. A destination for throwing instructions // 3. An instruction that itself rethrows to another 'catch' - assert(ControlFlowStack.back().first == EHPadStack.back()); + assert(ControlFlowStack.back().first == TryStack.back()); std::string Label = "label/catch" + utostr(ControlFlowStack.pop_back_val().first) + ": "; - EHPadStack.pop_back(); + TryStack.pop_back(); EHInstStack.pop_back(); uint64_t Depth = MI->getOperand(0).getImm(); if (Depth >= ControlFlowStack.size()) { 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 @@ -86,6 +86,9 @@ const MachineBasicBlock *MBB); unsigned getDelegateDepth(const SmallVectorImpl &Stack, const MachineBasicBlock *MBB); + unsigned + getRethrowDepth(const SmallVectorImpl &Stack, + const SmallVectorImpl &EHPadStack); void rewriteDepthImmediates(MachineFunction &MF); void fixEndsAtEndOfFunction(MachineFunction &MF); void cleanupFunctionData(MachineFunction &MF); @@ -1551,9 +1554,48 @@ return Depth; } +unsigned WebAssemblyCFGStackify::getRethrowDepth( + const SmallVectorImpl &Stack, + const SmallVectorImpl &EHPadStack) { + unsigned Depth = 0; + // In our current implementation, rethrows always rethrow the exception caught + // by the innermost enclosing catch. This means while traversing Stack in the + // reverse direction, when we encounter END_TRY, we should check if the + // END_TRY corresponds to the current innermost EH pad. For example: + // try + // ... + // catch ;; (a) + // try + // rethrow 1 ;; (b) + // catch ;; (c) + // rethrow 0 ;; (d) + // end ;; (e) + // end ;; (f) + // + // When we are at 'rethrow' (d), while reversly traersign Stack the first + // 'end' we encounter is the 'end' (e), which corresponds to the 'catch' (c). + // And 'rethrow' (d) rethrows the exception caught by 'catch' (c), so we stop + // there and the depth should be 0. But when we are at 'rethrow' (b), it + // rethrows the exception caught by 'catch' (a), so when traversing Stack + // reversely, we should skip the 'end' (e) and choose 'end' (f), which + // corresponds to 'catch' (a). + for (auto X : reverse(Stack)) { + const MachineInstr *End = X.second; + if (End->getOpcode() == WebAssembly::END_TRY) { + auto *EHPad = TryToEHPad[EndToBegin[End]]; + if (EHPadStack.back() == EHPad) + break; + } + ++Depth; + } + assert(Depth < Stack.size() && "Rethrow destination should be in scope"); + return Depth; +} + void WebAssemblyCFGStackify::rewriteDepthImmediates(MachineFunction &MF) { // Now rewrite references to basic blocks to be depth immediates. SmallVector Stack; + SmallVector EHPadStack; for (auto &MBB : reverse(MF)) { for (auto I = MBB.rbegin(), E = MBB.rend(); I != E; ++I) { MachineInstr &MI = *I; @@ -1575,16 +1617,28 @@ Stack.push_back(std::make_pair(&MBB, &MI)); break; - case WebAssembly::END_TRY: + case WebAssembly::END_TRY: { // We handle DELEGATE in the default level, because DELEGATE has // immediate operands to rewrite. Stack.push_back(std::make_pair(&MBB, &MI)); + auto *EHPad = TryToEHPad[EndToBegin[&MI]]; + EHPadStack.push_back(EHPad); break; + } case WebAssembly::END_LOOP: Stack.push_back(std::make_pair(EndToBegin[&MI]->getParent(), &MI)); break; + case WebAssembly::CATCH: + case WebAssembly::CATCH_ALL: + EHPadStack.pop_back(); + break; + + case WebAssembly::RETHROW: + MI.getOperand(0).setImm(getRethrowDepth(Stack, EHPadStack)); + break; + default: if (MI.isTerminator()) { // Rewrite MBB operands to be depth immediates. diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td --- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td +++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td @@ -133,8 +133,8 @@ "throw \t$tag", "throw \t$tag", 0x08>; defm RETHROW : NRI<(outs), (ins i32imm:$depth), [], "rethrow \t$depth", 0x09>; } // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 -// For C++ support, we only rethrow the latest exception, thus always setting -// the depth to 0. +// The depth argument will be computed in CFGStackify. We set it to 0 here for +// now. def : Pat<(int_wasm_rethrow), (RETHROW 0)>; // Region within which an exception is caught: 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 @@ -119,7 +119,7 @@ ; CHECK: rethrow 0 # down to catch[[C0:[0-9]+]] ; CHECK: end_try ; CHECK: end_block # label[[L2]]: -; CHECK: rethrow 0 # down to catch[[C0]] +; CHECK: rethrow 1 # down to catch[[C0]] ; CHECK: catch_all # catch[[C0]]: ; CHECK: call __cxa_end_catch ; CHECK: rethrow 0 # to caller @@ -128,7 +128,7 @@ ; CHECK: br 2 # 2: down to label[[L1]] ; CHECK: end_try ; CHECK: end_block # label[[L0]]: -; CHECK: rethrow 0 # to caller +; CHECK: rethrow 1 # to caller ; CHECK: end_block # label[[L1]]: ; CHECK: call __cxa_end_catch ; CHECK: end_try diff --git a/llvm/test/CodeGen/WebAssembly/exception.mir b/llvm/test/CodeGen/WebAssembly/exception.mir --- a/llvm/test/CodeGen/WebAssembly/exception.mir +++ b/llvm/test/CodeGen/WebAssembly/exception.mir @@ -12,6 +12,9 @@ define void @unreachable_ehpad_test() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) { ret void } + define void @rethrow_arg_test() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) { + ret void + } ... --- @@ -24,6 +27,7 @@ body: | bb.0: ; TRY should be before EH_LABEL wrappers of throwing calls + ; CHECK: bb.0 ; CHECK: TRY ; CHECK-NEXT: EH_LABEL ; CHECK-NEXT: CALL @foo @@ -38,15 +42,17 @@ ; predecessors: %bb.0 successors: %bb.2 ; CATCH_ALL should be after an EH_LABEL at the beginning of an EH pad + ; CHECK: bb.1 ; CHECK: EH_LABEL ; CHECK-NEXT: CATCH_ALL EH_LABEL - CATCHRET %bb.2, %bb.0, implicit-def dead $arguments + CATCHRET %bb.2, %bb.1, implicit-def dead $arguments bb.2: ; predecessors: %bb.0, %bb.1 RETURN implicit-def dead $arguments ... + --- # Unreachable EH pads should be removed by LateEHPrepare. # CHECK-LABEL: name: unreachable_ehpad_test @@ -64,10 +70,63 @@ bb.1 (landing-pad): successors: %bb.2 EH_LABEL - CATCHRET %bb.2, %bb.0, implicit-def dead $arguments + CATCHRET %bb.2, %bb.1, implicit-def dead $arguments ; CHECK: bb.2 bb.2: ; predecessors: %bb.0, %bb.1 RETURN implicit-def dead $arguments ... + +--- +# CHECK-LABEL: name: rethrow_arg_test +name: rethrow_arg_test +liveins: + - { reg: '$arguments' } +body: | + bb.0: + successors: %bb.1, %bb.4 + ; CHECK: bb.0 + ; CHECK: TRY + EH_LABEL + CALL @foo, implicit-def dead $arguments, implicit $sp32, implicit $sp64 + EH_LABEL + BR %bb.4, implicit-def dead $arguments + + bb.1 (landing-pad): + ; predecessors: %bb.0 + successors: %bb.2 + ; CHECK: bb.1 + ; CHECK: CATCH + ; CHECK: TRY + ; This RETHROW rethrows the exception caught by this BB's CATCH, but after + ; CFGStackify a TRY is placed between the CATCH and this RETHROW, so after + ; CFGStackify its ; immediate argument should become not 0, but 1. + ; CHECK: RETHROW 1 + EH_LABEL + %0:i32 = CATCH &__cpp_exception, implicit-def dead $arguments + RETHROW 0, implicit-def dead $arguments + + bb.2 (landing-pad): + ; predecessors: %bb.1 + successors: %bb.3 + ; CHECK: bb.2 + ; CHECK: CATCH + ; CHECK: RETHROW 0 + EH_LABEL + %1:i32 = CATCH &__cpp_exception, implicit-def dead $arguments + RETHROW 0, implicit-def dead $arguments + CATCHRET %bb.3, %bb.2, implicit-def dead $arguments + + bb.3: + ; predecessors: %bb.2 + successors: %bb.4 + CATCHRET %bb.4, %bb.1, implicit-def dead $arguments + + bb.4: + ; predecessors: %bb.0, %bb.3 + ; CHECK: bb.4 + ; CHECK: END_TRY + ; CHECK: END_TRY + RETURN implicit-def dead $arguments +