[clang] [Clang][CodeGen] Use ptrtoaddr for pointer diff (PR #210729)

[Nikita Popov via cfe-commits]

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@@ -87,37 +87,45 @@ global char* test_add_global(global char* x, ptrdiff_t y) {
 }
 
 //SZ32: define{{.*}} i32 @test_sub_local(ptr addrspace(3) noundef %x, ptr addrspace(3) noundef %y)
-//SZ32: ptrtoint ptr addrspace(3) %{{.*}} to i32
-//SZ32: ptrtoint ptr addrspace(3) %{{.*}} to i32
-//SZ64: define{{.*}} i64 @test_sub_local(ptr addrspace(3) noundef %x, ptr addrspace(3) noundef %y)
-//SZ64: ptrtoint ptr addrspace(3) %{{.*}} to i64
-//SZ64: ptrtoint ptr addrspace(3) %{{.*}} to i64
+//SZ32: ptrtoaddr ptr addrspace(3) %{{.*}} to i32
+//SZ32: ptrtoaddr ptr addrspace(3) %{{.*}} to i32
+//SZ64ONLY: define{{.*}} i64 @test_sub_local(ptr addrspace(3) noundef %x, ptr addrspace(3) noundef %y)
+//SZ64ONLY: ptrtoaddr ptr addrspace(3) %{{.*}} to i64
+//SZ64ONLY: ptrtoaddr ptr addrspace(3) %{{.*}} to i64
+//AMDGCN: define{{.*}} i64 @test_sub_local(ptr addrspace(3) noundef %x, ptr addrspace(3) noundef %y)
+//AMDGCN: ptrtoaddr ptr addrspace(3) %{{.*}} to i32
+//AMDGCN: ptrtoaddr ptr addrspace(3) %{{.*}} to i32
+//AMDGCN: zext i32 %{{.*}} to i64
+//AMDGCN: zext i32 %{{.*}} to i64
 ptrdiff_t test_sub_local(local char* x, local char *y) {
   return x - y;
 }
 
 //SZ32: define{{.*}} i32 @test_sub_private(ptr noundef %x, ptr noundef %y)
-//SZ32: ptrtoint ptr %{{.*}} to i32
-//SZ32: ptrtoint ptr %{{.*}} to i32
+//SZ32: ptrtoaddr ptr %{{.*}} to i32
+//SZ32: ptrtoaddr ptr %{{.*}} to i32
 //SZ64ONLY: define{{.*}} i64 @test_sub_private(ptr noundef %x, ptr noundef %y)
-//SZ64ONLY: ptrtoint ptr %{{.*}} to i64
-//SZ64ONLY: ptrtoint ptr %{{.*}} to i64
+//SZ64ONLY: ptrtoaddr ptr %{{.*}} to i64
+//SZ64ONLY: ptrtoaddr ptr %{{.*}} to i64
 //AMDGCN: define{{.*}} i64 @test_sub_private(ptr addrspace(5) noundef %x, ptr addrspace(5) noundef %y)
-//AMDGCN: ptrtoint ptr addrspace(5) %{{.*}} to i64
-//AMDGCN: ptrtoint ptr addrspace(5) %{{.*}} to i64
+//AMDGCN: ptrtoaddr ptr addrspace(5) %{{.*}} to i32
+//AMDGCN: ptrtoaddr ptr addrspace(5) %{{.*}} to i32
+//AMDGCN: zext i32 %{{.*}} to i64
+//AMDGCN: zext i32 %{{.*}} to i64
 ptrdiff_t test_sub_private(private char* x, private char *y) {
   return x - y;
 }
 
 //SZ32: define{{.*}} i32 @test_sub_mix(ptr noundef %x, ptr addrspace(4) noundef %y)
-//SZ32: ptrtoint ptr %{{.*}} to i32
-//SZ32: ptrtoint ptr addrspace(4) %{{.*}} to i32
+//SZ32: ptrtoaddr ptr %{{.*}} to i32
+//SZ32: ptrtoaddr ptr addrspace(4) %{{.*}} to i32
 //SZ64ONLY: define{{.*}} i64 @test_sub_mix(ptr noundef %x, ptr addrspace(4) noundef %y)
-//SZ64ONLY: ptrtoint ptr %{{.*}} to i64
-//SZ64ONLY: ptrtoint ptr addrspace(4) %{{.*}} to i64
+//SZ64ONLY: ptrtoaddr ptr %{{.*}} to i64
+//SZ64ONLY: ptrtoaddr ptr addrspace(4) %{{.*}} to i64
 //AMDGCN: define{{.*}} i64 @test_sub_mix(ptr addrspace(5) noundef %x, ptr noundef %y)
-//AMDGCN: ptrtoint ptr addrspace(5) %{{.*}} to i64
-//AMDGCN: ptrtoint ptr %{{.*}} to i64
+//AMDGCN: ptrtoaddr ptr addrspace(5) %{{.*}} to i32
+//AMDGCN: ptrtoaddr ptr %{{.*}} to i64
+//AMDGCN: zext i32 %{{.*}} to i64
----------------
nikic wrote:

Huh, this is weird. And probably broken before this change, just more obvious now? This would only do something reasonable if casting from addrspace 5 to 0 would make the top bits zero, which (I believe) is not the case.

I think for this specific case it might have been correct to truncate to the smaller address space. Though more generally it seems like subtraction between address spaces needs to be handled by addrspacecasting to a common address space.

cc @arsenm 

https://github.com/llvm/llvm-project/pull/210729