[X86][RTM] _xabort() should not have "noreturn" attribute

[AsafBadouh]

Summary

calling to _xabort() outside RTM execution section should be "nop".

Simplify CFG check call with noreturn attribute and mark the rest of the block as "unreachable".

[aaboud]

Can you add a LIT test?
Like this one:

void f1();
void f2() {
  _xbegin();
  _xabort();
  f1();
}

And check that we are generating the call to f1;

[AsafBadouh]

test added

[DavidKreitzer]

lgtm, Asaf.

[hliao]

LGTM

llvm/trunk/include/llvm/IR/IntrinsicsX86.td

 // RTM intrinsics. Transactional Memory support.
 
 let TargetPrefix = "x86" in {  // All intrinsics start with "llvm.x86.".
   def int_x86_xbegin : GCCBuiltin<"__builtin_ia32_xbegin">,
               Intrinsic<[llvm_i32_ty], [], []>;
   def int_x86_xend : GCCBuiltin<"__builtin_ia32_xend">,
               Intrinsic<[], [], []>;
   def int_x86_xabort : GCCBuiltin<"__builtin_ia32_xabort">,
-              Intrinsic<[], [llvm_i8_ty], [IntrNoReturn]>;
+              Intrinsic<[], [llvm_i8_ty], []>;
   def int_x86_xtest : GCCBuiltin<"__builtin_ia32_xtest">,
               Intrinsic<[llvm_i32_ty], [], []>;
 }
 
 //===----------------------------------------------------------------------===//
 // AVX512
 
 // Mask ops

llvm/trunk/test/CodeGen/X86/rtm.ll

 ; RUN: llc < %s -mattr=+rtm -mtriple=x86_64-unknown-unknown | FileCheck %s
 
 declare i32 @llvm.x86.xbegin() nounwind
 declare void @llvm.x86.xend() nounwind
-declare void @llvm.x86.xabort(i8) noreturn nounwind
+declare void @llvm.x86.xabort(i8) nounwind
+declare void @f1()
 
 define i32 @test_xbegin() nounwind uwtable {
 entry:
   %0 = tail call i32 @llvm.x86.xbegin() nounwind
   ret i32 %0
 ; CHECK: test_xbegin
 ; CHECK: xbegin [[LABEL:.*BB.*]]
 ; CHECK: [[LABEL]]:
 }
 
 define void @test_xend() nounwind uwtable {
 entry:
   tail call void @llvm.x86.xend() nounwind
   ret void
 ; CHECK: test_xend
 ; CHECK: xend
 }
 
 define void @test_xabort() nounwind uwtable {
 entry:
   tail call void @llvm.x86.xabort(i8 2)
-  unreachable
+  ret void
 ; CHECK: test_xabort
 ; CHECK: xabort $2
 }
+
+define void @f2(i32 %x) nounwind uwtable {
+entry:
+  %x.addr = alloca i32, align 4
+  store i32 %x, i32* %x.addr, align 4
+  call void @llvm.x86.xabort(i8 1)
+  call void @f1()
+  ret void
+; CHECK-LABEL: f2
+; CHECK: xabort  $1
+; CHECK: callq   f1
+}
  
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