[CodeGen] Add "noreturn" attirbute to _Unwind_Resume

Currently 'resume' is lowered to _Unwind_Resume with out "noreturn" attribute. Semantically _Unwind_Resume  library call is expected to never return and should be marked as such. Though I didn't find any changes in behavior of existing tests there will be a difference once https://reviews.llvm.org/D79485 lands.

I was not able to come up with the test case anything better than just checking for presence of "noreturn" attribute. Please let me know if there is a better way to test the change.

Reviewed By: xbolva00

Differential Revision: https://reviews.llvm.org/D93682

Author: Evgeniy Brevnov

llvm/lib/CodeGen/DwarfEHPrepare.cpp

@@ -235,6 +235,7 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
     CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
 
     // We never expect _Unwind_Resume to return.
+    CI->setDoesNotReturn();
     new UnreachableInst(Ctx, UnwindBB);
     return true;
   }
@@ -260,6 +261,7 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
   CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
 
   // We never expect _Unwind_Resume to return.
+  CI->setDoesNotReturn();
   new UnreachableInst(Ctx, UnwindBB);
   return true;
 }

llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-invoke-probabilities.ll

@@ -11,7 +11,7 @@ declare i32 @hoge(...)
 define void @pluto() align 2 personality i8* bitcast (i32 (...)* @hoge to i8*) {
 ; CHECK-LABEL: @pluto
 ; CHECK: bb.1.bb
-; CHECK: successors: %bb.2(0x40000000), %bb.3(0x40000000)
+; CHECK: successors: %bb.2(0x00000000), %bb.3(0x80000000)
 ; CHECK: EH_LABEL <mcsymbol >
 ; CHECK: G_BR %bb.2
 

llvm/test/CodeGen/Generic/dwarf_eh_resume.ll

@@ -0,0 +1,23 @@
+; RUN: llc %s -stop-after=irtranslator -o - | FileCheck %s
+
+declare i32 @hoge(...)
+
+; Check that 'resume' is lowered to _Unwind_Resume which marked as 'noreturn'
+define void @pluto() align 2 personality i8* bitcast (i32 (...)* @hoge to i8*) {
+;CHECK: call void @_Unwind_Resume(i8* %exn.obj) [[A:#.*]]
+;CHECK: attributes [[A]] = { noreturn }
+bb:
+  invoke void @spam()
+          to label %bb1 unwind label %bb2
+
+bb1:                                              ; preds = %bb
+  ret void
+
+bb2:                                              ; preds = %bb
+  %tmp = landingpad { i8*, i32 }
+          cleanup
+  resume { i8*, i32 } %tmp
+
+}
+
+declare void @spam()