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[WebAssembly] Don't copy noreturn attr to invokes 

When we create an invoke wrapper call, if the original call instruction
has a `noreturn` attribute, we shouldn't copy it, because we expect
invoke wrapper calls to return. This generated incorrect `free` call
before an invoke wrapper call that calls `__cxa_throw`, because
`__cxa_throw` has `noreturn` attribute.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D118274
This commit is contained in:
Heejin Ahn 2022-01-25 21:41:43 -08:00
parent d9517efbb3
commit 786da40667
2 changed files with 54 additions and 0 deletions
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3
llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
View File

@ -560,6 +560,9 @@ Value *WebAssemblyLowerEmscriptenEHSjLj::wrapInvoke(CallBase *CI) {
NEltArg = NEltArg.getValue() + 1;
FnAttrs.addAllocSizeAttr(SizeArg, NEltArg);
}
// In case the callee has 'noreturn' attribute, We need to remove it, because
// we expect invoke wrappers to return.
FnAttrs.removeAttribute(Attribute::NoReturn);
// Reconstruct the AttributesList based on the vector we constructed.
AttributeList NewCallAL = AttributeList::get(

51
llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll
View File

@ -7,6 +7,7 @@ target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
target triple = "wasm32-unknown-unknown"
%struct.__jmp_buf_tag = type { [6 x i32], i32, [32 x i32] }
@_ZTIi = external constant i8*
; There is a function call (@foo) that can either throw an exception or longjmp
; and there is also a setjmp call. When @foo throws, we have to check both for
@ -220,6 +221,54 @@ return: ; preds = %entry, %if.end
; CHECK-NEXT: unreachable
}
; int jmpval = setjmp(buf);
; if (jmpval != 0)
; return;
; try {
; throw 3;
; } catch (...) {
; }
define void @setjmp_with_throw_try_catch() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
; CHECK-LABEL: @setjmp_with_throw_try_catch
entry:
%buf = alloca [1 x %struct.__jmp_buf_tag], align 16
%arraydecay = getelementptr inbounds [1 x %struct.__jmp_buf_tag], [1 x %struct.__jmp_buf_tag]* %buf, i32 0, i32 0
%call = call i32 @setjmp(%struct.__jmp_buf_tag* %arraydecay) #0
%cmp = icmp ne i32 %call, 0
br i1 %cmp, label %try.cont, label %if.end
if.end: ; preds = %entry
%exception = call i8* @__cxa_allocate_exception(i32 4) #2
%0 = bitcast i8* %exception to i32*
store i32 3, i32* %0, align 16
invoke void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #1
to label %unreachable unwind label %lpad
; When invoke @__cxa_throw is converted to a call to the invoke wrapper,
; "noreturn" attribute should be removed, and there should be no 'free' call
; before the call. We insert a 'free' call that frees 'setjmpTable' before every
; function-exiting instruction. And invoke wrapper calls shouldn't be treated as
; noreturn instructions, because they are supposed to return.
; CHECK: if.end:
; CHECK-NOT: tail call void @free
; CHECK-NOT: call cc99 void @"__invoke_void_i8*_i8*_i8*"(void (i8*, i8*, i8*)* @__cxa_throw, i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #
; CHECK: call cc99 void @"__invoke_void_i8*_i8*_i8*"(void (i8*, i8*, i8*)* @__cxa_throw, i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null)
lpad: ; preds = %if.end
%1 = landingpad { i8*, i32 }
catch i8* null
%2 = extractvalue { i8*, i32 } %1, 0
%3 = extractvalue { i8*, i32 } %1, 1
%4 = call i8* @__cxa_begin_catch(i8* %2) #2
call void @__cxa_end_catch()
br label %try.cont
try.cont: ; preds = %entry, %lpad
ret void
unreachable: ; preds = %if.end
unreachable
}
declare void @foo()
; Function Attrs: returns_twice
declare i32 @setjmp(%struct.__jmp_buf_tag*)
@ -229,6 +278,8 @@ declare i32 @__gxx_personality_v0(...)
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
declare void @__cxa_throw(i8*, i8*, i8*)
declare i8* @__cxa_allocate_exception(i32)
attributes #0 = { returns_twice }
attributes #1 = { noreturn }
attributes #2 = { nounwind }