[WebAssembly] Fix allocsize attribute in sjlj lowering

[loladiro]

Summary

The allocsize attribute refers to call parameters by index.
Thus, when we add the extra parameter in sjlj lowering, we
need to increment the referenced paramater in the allocsize
attribute to avoid angering the Verifier.

[aheejin]

This comment was removed by aheejin.

llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll

207

Real nit: Doesn't matter for this test case, but maybe it would make more sense for this file to return i8*, because it has allocsize attribute

[aheejin]

Thank you for fixing this too!

(I added D65463 as a parent revision by mistake and deleted it, sorry; I was confused and thought this was related to that CL first, but this is not)

llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp

Value *WebAssemblyLowerEmscriptenEHSjLj::wrapInvoke(CallOrInvoke *CI) {
   const AttributeList &InvokeAL = CI->getAttributes();
 
   // No attributes for the callee pointer.
   ArgAttributes.push_back(AttributeSet());
   // Copy the argument attributes from the original
   for (unsigned I = 0, E = CI->getNumArgOperands(); I < E; ++I)
     ArgAttributes.push_back(InvokeAL.getParamAttributes(I));
 
+  AttrBuilder FnAttrs(InvokeAL.getFnAttributes());
+  if (FnAttrs.contains(Attribute::AllocSize)) {
+    // The allocsize attribute (if any) referes to parameters by index and needs
+    // to be adjusted.
+    unsigned SizeArg;
+    Optional<unsigned> NEltArg;
+    std::tie(SizeArg, NEltArg) = FnAttrs.getAllocSizeArgs();
+    SizeArg += 1;
+    if (NEltArg.hasValue())
+      NEltArg = NEltArg.getValue() + 1;
+    FnAttrs.addAllocSizeAttr(SizeArg, NEltArg);
+  }
+
   // Reconstruct the AttributesList based on the vector we constructed.
   AttributeList NewCallAL =
-      AttributeList::get(C, InvokeAL.getFnAttributes(),
+      AttributeList::get(C, AttributeSet::get(C, FnAttrs),
                          InvokeAL.getRetAttributes(), ArgAttributes);
   NewCall->setAttributes(NewCallAL);
 
   CI->replaceAllUsesWith(NewCall);
 
   // Post-invoke
   // %__THREW__.val = __THREW__; __THREW__ = 0;
   Value *Threw =

llvm/test/CodeGen/WebAssembly/lower-em-sjlj.ll

 
 ; CHECK: entry.split.split:
 ; CHECK-NEXT: %[[BUF:.*]] = bitcast i32* %[[SETJMP_TABLE]] to i8*
 ; CHECK-NEXT: tail call void @free(i8* %[[BUF]])
 ; CHECK-NEXT: ret void
 }
 
 ; Test a case when a function call is within try-catch, after a setjmp
-define hidden void @exception_and_longjmp() #3 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+define hidden void @exception_and_longjmp() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
 ; CHECK-LABEL: @exception_and_longjmp
 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
   invoke void @foo()
           to label %try.cont unwind label %lpad
 

 ; Inline assembly should not generate __invoke wrappers.
 ; Doing so would fail as inline assembly cannot be passed as a function pointer.
 ; CHECK: call void asm sideeffect "", ""()
 ; CHECK-NOT: __invoke_void
   call void asm sideeffect "", ""()
   ret void
 }
 
+; Test that the allocsize attribute is being transformed properly
+declare void @allocator(i32, %struct.__jmp_buf_tag*) #3
+define hidden void @allocsize() {
+; CHECK-LABEL: @allocsize
+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
+; CHECK: void @"__invoke_void_i32_%struct.__jmp_buf_tag*"([[ARGS:.*]]) #[[ALLOCSIZE_ATTR:[0-9]+]]
+  call void @allocator(i32 20, %struct.__jmp_buf_tag* %arraydecay) #3
+  ret void
+}
+
 declare void @foo()
 ; Function Attrs: returns_twice
 declare i32 @setjmp(%struct.__jmp_buf_tag*) #0
 ; Function Attrs: noreturn
 declare void @longjmp(%struct.__jmp_buf_tag*, i32) #1
 declare i32 @__gxx_personality_v0(...)
 declare i8* @__cxa_begin_catch(i8*)
 declare void @__cxa_end_catch()
 declare i8* @malloc(i32)
 declare void @free(i8*)
 
 ; JS glue functions and invoke wrappers declaration
 ; CHECK-DAG: declare i32 @getTempRet0()
 ; CHECK-DAG: declare void @setTempRet0(i32)
 ; CHECK-DAG: declare i32* @saveSetjmp(%struct.__jmp_buf_tag*, i32, i32*, i32)
 ; CHECK-DAG: declare i32 @testSetjmp(i32, i32*, i32)
 ; CHECK-DAG: declare void @emscripten_longjmp_jmpbuf(%struct.__jmp_buf_tag*, i32)
 ; CHECK-DAG: declare void @emscripten_longjmp(i32, i32)
 ; CHECK-DAG: declare void @__invoke_void(void ()*)
 ; CHECK-DAG: declare void @"__invoke_void_%struct.__jmp_buf_tag*_i32"(void (%struct.__jmp_buf_tag*, i32)*, %struct.__jmp_buf_tag*, i32)
 
 attributes #0 = { returns_twice }
 attributes #1 = { noreturn }
 attributes #2 = { nounwind }
+attributes #3 = { allocsize(0) }
+; CHECK: attributes #[[ALLOCSIZE_ATTR]] = { allocsize(1) }