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Revert "[WebAssembly] Rethrow longjmp in EH handling if EmSjLj is enabled" 

This reverts commit b7b4ebbcfa.

Reason: This breaks several code-size tests in Emscripten test suite
because this exports `emscripten_longjmp` for programs that didn't do it
before.
This commit is contained in:
Heejin Ahn 2021-09-14 12:58:09 -07:00
parent 3ce1b9631a
commit 468c4409f6
2 changed files with 2 additions and 77 deletions
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20
llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
View File

@ -959,18 +959,6 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runOnModule(Module &M) {
}
}
// Above, we registered emscripten_longjmp function only when it SjLj is
// actually used. But there is a case we need emscripten_longjmp when we
// rethrow longjmps after checking for an Emscripten exception. Refer to
// runEHOnFunction for details.
if (EnableEmEH && EnableEmSjLj && !EmLongjmpF) {
// Register emscripten_longjmp function
FunctionType *FTy = FunctionType::get(
IRB.getVoidTy(), {getAddrIntType(&M), IRB.getInt32Ty()}, false);
EmLongjmpF = getEmscriptenFunction(FTy, "emscripten_longjmp", &M);
EmLongjmpF->addFnAttr(Attribute::NoReturn);
}
// Exception handling transformation
if (EnableEmEH) {
for (Function &F : M) {
@ -1048,11 +1036,6 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runEHOnFunction(Function &F) {
// value is 0 when nothing happened, 1 when an exception is thrown, and
// other values when longjmp is thrown.
//
// Note that we do this whenever -enable-emscripten-sjlj is on, regardless
// of whether there is actual usage of setjmp/longjmp within the module.
// Because we use wasm-ld to link files, what we see here is not the whole
// program, and there can be a longjmp call in another file.
//
// if (%__THREW__.val == 0 || %__THREW__.val == 1)
// goto %tail
// else
@ -1064,7 +1047,8 @@ bool WebAssemblyLowerEmscriptenEHSjLj::runEHOnFunction(Function &F) {
//
// tail: ;; Nothing happened or an exception is thrown
// ... Continue exception handling ...
if (EnableEmSjLj && !SetjmpUsers.count(&F) && canLongjmp(Callee)) {
if (DoSjLj && EnableEmSjLj && !SetjmpUsers.count(&F) &&
canLongjmp(Callee)) {
// Create longjmp.rethrow BB once and share it within the function
if (!RethrowLongjmpBB) {
RethrowLongjmpBB = BasicBlock::Create(C, "rethrow.longjmp", &F);

59
llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj-sjlj-not-used.ll
View File

@ -1,59 +0,0 @@
; RUN: opt < %s -wasm-lower-em-ehsjlj -enable-emscripten-cxx-exceptions -enable-emscripten-sjlj -S | FileCheck %s
; RUN: llc < %s -enable-emscripten-cxx-exceptions -enable-emscripten-sjlj -verify-machineinstrs
target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"
; The same test with the same function in lower-em-ehsjlj.ll, both the
; Emscripten EH and Emscripten SjLj are enabled in the same way, and this
; function only does exception handling. The difference is that this module does
; not contain any calls to setjmp or longjmp.
;
; But we still have to check if the thrown value is longjmp and and if so
; rethrow it by calling @emscripten_longjmp, because we link object files using
; wasm-ld, so the module we see in LowerEmscriptenEHSjLj pass is not the whole
; program and there can be a longjmp call within another file.
define void @rethrow_longjmp() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
; CHECK-LABEL: @rethrow_longjmp
entry:
invoke void @foo()
to label %try.cont unwind label %lpad
; CHECK: entry:
; CHECK: %cmp.eq.one = icmp eq i32 %__THREW__.val, 1
; CHECK-NEXT: %cmp.eq.zero = icmp eq i32 %__THREW__.val, 0
; CHECK-NEXT: %or = or i1 %cmp.eq.zero, %cmp.eq.one
; CHECK-NEXT: br i1 %or, label %tail, label %rethrow.longjmp
; CHECK: try.cont:
; CHECK-NEXT: %phi = phi i32 [ undef, %tail ], [ undef, %lpad ]
; CHECK-NEXT: ret void
; CHECK: rethrow.longjmp:
; CHECK-NEXT: %threw.phi = phi i32 [ %__THREW__.val, %entry ]
; CHECK-NEXT: %__threwValue.val = load i32, i32* @__threwValue, align 4
; CHECK-NEXT: call void @emscripten_longjmp(i32 %threw.phi, i32 %__threwValue.val
; CHECK-NEXT: unreachable
; CHECK: tail:
; CHECK-NEXT: %cmp = icmp eq i32 %__THREW__.val, 1
; CHECK-NEXT: br i1 %cmp, label %lpad, label %try.cont
lpad: ; preds = %entry
%0 = landingpad { i8*, i32 }
catch i8* null
%1 = extractvalue { i8*, i32 } %0, 0
%2 = extractvalue { i8*, i32 } %0, 1
%3 = call i8* @__cxa_begin_catch(i8* %1) #5
call void @__cxa_end_catch()
br label %try.cont
try.cont: ; preds = %lpad, %entry
%phi = phi i32 [ undef, %entry ], [ undef, %lpad ]
ret void
}
declare void @foo()
declare i32 @__gxx_personality_v0(...)
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
declare void @__cxa_throw(i8*, i8*, i8*)