[RS4GC] Strengthen coverage: add more tests

[anna]

Summary

Add tests for cases where we have zero coverage in RS4GC.

[sanjoy]

Thanks Anna, this is great!

Can you check if it makes sense to put statepoint-attrs.ll into some pre-existing file? If not a separate file is fine.

[anna]

In D25341#563897, @sanjoy wrote:

Thanks Anna, this is great!

Can you check if it makes sense to put statepoint-attrs.ll into some pre-existing file? If not a separate file is fine.

Hi Sanjoy,

Yes, all other test files were for some specific test scenarios.

More importantly the statepoint-attrs.ll is a somewhat flaky test, and can have unintended consequences with multiple tests/function declarations in a file. The attributes list (attribute #1) can be modified to another attribute list during opt, if we were to have more tests, or function declarations. Example:
After opt:

call token (i64, i32, void (i8 addrspace(1)*)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidp1i8f(i64 2882400000, i32 0, void (i8 addrspace(1)*)* @f, i32 1, i32 0, i8 addrspace(1)* %arg, i32 0, i32 0, i8 addrspace(1)* %arg) #2

attributes #1 = {.. some new attributes added to some func declaration..}
attributes #2 = { norecurse noimplicitfloat }
...

The CHECK would fail (since `CHECK` is for the specific `attribute #1`). I'm not sure if there is any way to get around this, i.e. force attribute list to remain the same.

test/Transforms/RewriteStatepointsForGC/deopt-lowering-attrs.ll

 ; CHECK: @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @baz, i32 0, i32 0, i32 0, i32 1, i32 13)
 
 entry:
   call void @foo() [ "deopt"(i32 57) ]
   call void @bar() [ "deopt"(i32 42) ]
   call void @baz() [ "deopt"(i32 13) ]
   ret void
 }
+
+; add deopt-lowering attribute as part of callsite
+define void @test2() gc "statepoint-example" {
+; CHECK-LABEL: @test2(
+; CHECK: @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @foo, i32 0, i32 2, i32 0, i32 1, i32 57)
+
+entry:
+  call void @foo()  "deopt-lowering"="live-in"  [ "deopt"(i32 57) ]
+  ret void
+}
+

test/Transforms/RewriteStatepointsForGC/statepoint-attrs.ll

+; RUN: opt -S -rewrite-statepoints-for-gc < %s | FileCheck %s
+; Ensure statepoints copy (valid) attributes from callsites.
+
+declare void @f(i8 addrspace(1)* %obj)
+
+; copy over norecurse noimplicitfloat to statepoint call
+define void @test1(i8 addrspace(1)* %arg) gc "statepoint-example" {
+; CHECK-LABEL: test1(
+; CHECK: call token (i64, i32, void (i8 addrspace(1)*)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidp1i8f(i64 2882400000, i32 0, void (i8 addrspace(1)*)* @f, i32 1, i32 0, i8 addrspace(1)* %arg, i32 0, i32 0, i8 addrspace(1)* %arg) #1
+
+ call void @f(i8 addrspace(1)* %arg) #1
+ ret void
+}
+
+
+attributes #1 = { norecurse noimplicitfloat }