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[WebAssembly] Improve pseudocode in LowerEmscriptenEHSjLj

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Both `__THREW__` and `__threwValue` are global variables, and we have
been distinguishing the global variable `__THREW__` and the loaded value
`%__THREW__.val` in comments but not doing it for `__threwValue`. Made
the pseudocode comments consistent for both variables.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D106524
This commit is contained in:
Heejin Ahn 2021-07-21 22:29:31 -07:00
parent e79fa78700
commit cd521f45d9
1 changed files with 14 additions and 10 deletions
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24
lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
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@ -49,6 +49,8 @@
/// means nothing occurred, 1 means an exception occurred, and other numbers
/// mean a longjmp occurred. In the case of longjmp, __THREW__ variable
/// indicates the corresponding setjmp buffer the longjmp corresponds to.
/// __threwValue is 0 for exceptions, and the argument to longjmp in case of
/// longjmp.
///
/// * Exception handling
///
@ -158,12 +160,13 @@
/// call @__invoke_SIG(func, arg1, arg2)
/// %__THREW__.val = __THREW__;
/// __THREW__ = 0;
/// if (%__THREW__.val != 0 & __threwValue != 0) {
/// %__threwValue.val = __threwValue;
/// if (%__THREW__.val != 0 & %__threwValue.val != 0) {
/// %label = testSetjmp(mem[%__THREW__.val], setjmpTable,
/// setjmpTableSize);
/// if (%label == 0)
/// emscripten_longjmp(%__THREW__.val, __threwValue);
/// setTempRet0(__threwValue);
/// emscripten_longjmp(%__THREW__.val, %__threwValue.val);
/// setTempRet0(%__threwValue.val);
/// } else {
/// %label = -1;
/// }
@ -177,7 +180,7 @@
/// testSetjmp examines setjmpTable to see if there is a matching setjmp
/// call. After calling an invoke wrapper, if a longjmp occurred, __THREW__
/// will be the address of matching jmp_buf buffer and __threwValue be the
/// second argument to longjmp. mem[__THREW__.val] is a setjmp ID that is
/// second argument to longjmp. mem[%__THREW__.val] is a setjmp ID that is
/// stored in saveSetjmp. testSetjmp returns a setjmp label, a unique ID to
/// each setjmp callsite. Label 0 means this longjmp buffer does not
/// correspond to one of the setjmp callsites in this function, so in this
@ -546,11 +549,12 @@ bool WebAssemblyLowerEmscriptenEHSjLj::isEmAsmCall(Module &M,
// Generate testSetjmp function call seqence with preamble and postamble.
// The code this generates is equivalent to the following JavaScript code:
// if (%__THREW__.val != 0 & threwValue != 0) {
// %__threwValue.val = __threwValue;
// if (%__THREW__.val != 0 & %__threwValue.val != 0) {
// %label = _testSetjmp(mem[%__THREW__.val], setjmpTable, setjmpTableSize);
// if (%label == 0)
// emscripten_longjmp(%__THREW__.val, threwValue);
// setTempRet0(threwValue);
// emscripten_longjmp(%__THREW__.val, %__threwValue.val);
// setTempRet0(%__threwValue.val);
// } else {
// %label = -1;
// }
@ -568,7 +572,7 @@ void WebAssemblyLowerEmscriptenEHSjLj::wrapTestSetjmp(
IRBuilder<> IRB(C);
IRB.SetCurrentDebugLocation(DL);
// if (%__THREW__.val != 0 & threwValue != 0)
// if (%__THREW__.val != 0 & %__threwValue.val != 0)
IRB.SetInsertPoint(BB);
BasicBlock *ThenBB1 = BasicBlock::Create(C, "if.then1", F);
BasicBlock *ElseBB1 = BasicBlock::Create(C, "if.else1", F);
@ -594,12 +598,12 @@ void WebAssemblyLowerEmscriptenEHSjLj::wrapTestSetjmp(
Value *Cmp2 = IRB.CreateICmpEQ(ThenLabel, IRB.getInt32(0));
IRB.CreateCondBr(Cmp2, ThenBB2, EndBB2);
// emscripten_longjmp(%__THREW__.val, threwValue);
// emscripten_longjmp(%__THREW__.val, %__threwValue.val);
IRB.SetInsertPoint(ThenBB2);
IRB.CreateCall(EmLongjmpF, {Threw, ThrewValue});
IRB.CreateUnreachable();
// setTempRet0(threwValue);
// setTempRet0(%__threwValue.val);
IRB.SetInsertPoint(EndBB2);
IRB.CreateCall(SetTempRet0Func, ThrewValue);
IRB.CreateBr(EndBB1);