[PATCH] D119271: clang: emit allocalign to LLVM for alloc_align attributes

[Roman Lebedev via Phabricator via cfe-commits]

lebedev.ri added inline comments.


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Comment at: clang/test/CodeGen/catch-alignment-assumption-attribute-alloc_align-on-function-variable.cpp:55
   // CHECK-NEXT:                        %[[ALIGNMENT_RELOADED:.*]] = load i64, i64* %[[ALIGNMENT_ADDR]], align 8
-  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call noundef i8** @[[PASSTHROUGH]](i8** noundef %[[X_RELOADED]], i64 noundef %[[ALIGNMENT_RELOADED]])
-  // CHECK-SANITIZE-NEXT:               %[[PTRINT:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64
-  // CHECK-SANITIZE-NEXT:               %[[MASK:.*]] = sub i64 %[[ALIGNMENT_RELOADED]], 1
-  // CHECK-SANITIZE-NEXT:               %[[MASKEDPTR:.*]] = and i64 %[[PTRINT]], %[[MASK]]
-  // CHECK-SANITIZE-NEXT:               %[[MASKCOND:.*]] = icmp eq i64 %[[MASKEDPTR]], 0
-  // CHECK-SANITIZE-NEXT:               %[[PTRINT_DUP:.*]] = ptrtoint i8** %[[X_RETURNED]] to i64, !nosanitize
-  // CHECK-SANITIZE-NEXT:               br i1 %[[MASKCOND]], label %[[CONT:.*]], label %[[HANDLER_ALIGNMENT_ASSUMPTION:[^,]+]],{{.*}} !nosanitize
-  // CHECK-SANITIZE:                  [[HANDLER_ALIGNMENT_ASSUMPTION]]:
-  // CHECK-SANITIZE-NORECOVER-NEXT:     call void @__ubsan_handle_alignment_assumption_abort(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 %[[ALIGNMENT_RELOADED]], i64 0){{.*}}, !nosanitize
-  // CHECK-SANITIZE-RECOVER-NEXT:       call void @__ubsan_handle_alignment_assumption(i8* bitcast ({ {{{.*}}}, {{{.*}}}, {{{.*}}}* }* @[[LINE_100_ALIGNMENT_ASSUMPTION]] to i8*), i64 %[[PTRINT_DUP]], i64 %[[ALIGNMENT_RELOADED]], i64 0){{.*}}, !nosanitize
-  // CHECK-SANITIZE-TRAP-NEXT:          call void @llvm.ubsantrap(i8 23){{.*}}, !nosanitize
-  // CHECK-SANITIZE-UNREACHABLE-NEXT:   unreachable, !nosanitize
-  // CHECK-SANITIZE:                  [[CONT]]:
-  // CHECK-NEXT:                        call void @llvm.assume(i1 true) [ "align"(i8** %[[X_RETURNED]], i64 %1) ]
+  // CHECK-NEXT:                        %[[X_RETURNED:.*]] = call noundef i8** @[[PASSTHROUGH]](i8** noundef %[[X_RELOADED]], i64 allocalign noundef %[[ALIGNMENT_RELOADED]])
   // CHECK-NEXT:                        ret i8** %[[X_RETURNED]]
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durin42 wrote:
> lebedev.ri wrote:
> > This is a regression, the old behavior was correct.
> I don't think so: we now (as of D121629) check the alignment of the returned pointer in the callee instead of the caller, and LLVM knows about allocalign implying an alignment at the callsite. So I think it's correctly optimizing away the sanitizer checks here.
> 
> You or @jyknight will need to correct me if my understanding is incorrect here, but my understanding was that this change was what motivated D121629 in the first place.
I'm saying that as the author of said test and it's behavior.


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  https://reviews.llvm.org/D119271/new/

https://reviews.llvm.org/D119271