[llvm] r206093 - Reenable use of TBAA during CodeGen

[Hal Finkel]

Author: hfinkel
Date: Fri Apr 11 20:26:00 2014
New Revision: 206093

URL: http://llvm.org/viewvc/llvm-project?rev=206093&view=rev
Log:
Reenable use of TBAA during CodeGen

We had disabled use of TBAA during CodeGen (even when otherwise using AA)
because the ptrtoint/inttoptr used by CGP for address sinking caused BasicAA to
miss basic type punning that it should catch (and, thus, we'd fail to override
TBAA when we should).

However, when AA is in use during CodeGen, CGP now uses normal GEPs and
bitcasts, instead of ptrtoint/inttoptr, when doing address sinking. As a
result, BasicAA should be able to make us do the right thing in the face of
type-punning, and it seems safe to enable use of TBAA again. self-hosting seems
fine on PPC64/Linux on the P7, with TBAA enabled and -misched=shuffle.

Note: We still don't update TBAA when merging stack slots, although because
BasicAA should now catch all such cases, this is no longer a blocking issue.
Nevertheless, I plan to commit code to deal with this properly in the near
future.

Modified:
    llvm/trunk/lib/CodeGen/ScheduleDAGInstrs.cpp
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/PowerPC/aa-tbaa.ll
    llvm/trunk/test/CodeGen/SystemZ/alias-01.ll

Modified: llvm/trunk/lib/CodeGen/ScheduleDAGInstrs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/ScheduleDAGInstrs.cpp?rev=206093&r1=206092&r2=206093&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/ScheduleDAGInstrs.cpp (original)
+++ llvm/trunk/lib/CodeGen/ScheduleDAGInstrs.cpp Fri Apr 11 20:26:00 2014
@@ -45,14 +45,8 @@ static cl::opt<bool> EnableAASchedMI("en
     cl::ZeroOrMore, cl::init(false),
     cl::desc("Enable use of AA during MI GAD construction"));
 
-// FIXME: Enable the use of TBAA. There are two known issues preventing this:
-//   1. Stack coloring does not update TBAA when merging allocas
-//   2. CGP inserts ptrtoint/inttoptr pairs when sinking address computations.
-//      Because BasicAA does not handle inttoptr, we'll often miss basic type
-//      punning idioms that we need to catch so we don't miscompile real-world
-//      code.
 static cl::opt<bool> UseTBAA("use-tbaa-in-sched-mi", cl::Hidden,
-    cl::init(false), cl::desc("Enable use of TBAA during MI GAD construction"));
+    cl::init(true), cl::desc("Enable use of TBAA during MI GAD construction"));
 
 ScheduleDAGInstrs::ScheduleDAGInstrs(MachineFunction &mf,
                                      const MachineLoopInfo &mli,

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=206093&r1=206092&r2=206093&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Fri Apr 11 20:26:00 2014
@@ -56,14 +56,8 @@ namespace {
     CombinerGlobalAA("combiner-global-alias-analysis", cl::Hidden,
                cl::desc("Enable DAG combiner's use of IR alias analysis"));
 
-// FIXME: Enable the use of TBAA. There are two known issues preventing this:
-//   1. Stack coloring does not update TBAA when merging allocas
-//   2. CGP inserts ptrtoint/inttoptr pairs when sinking address computations.
-//      Because BasicAA does not handle inttoptr, we'll often miss basic type
-//      punning idioms that we need to catch so we don't miscompile real-world
-//      code.
   static cl::opt<bool>
-    UseTBAA("combiner-use-tbaa", cl::Hidden, cl::init(false),
+    UseTBAA("combiner-use-tbaa", cl::Hidden, cl::init(true),
                cl::desc("Enable DAG combiner's use of TBAA"));
 
 #ifndef NDEBUG

Modified: llvm/trunk/test/CodeGen/PowerPC/aa-tbaa.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/aa-tbaa.ll?rev=206093&r1=206092&r2=206093&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/aa-tbaa.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/aa-tbaa.ll Fri Apr 11 20:26:00 2014
@@ -1,4 +1,4 @@
-; RUN: llc -enable-misched -misched=shuffle -enable-aa-sched-mi -post-RA-scheduler=0 -mcpu=ppc64 < %s | FileCheck %s
+; RUN: llc -enable-misched -misched=shuffle -enable-aa-sched-mi -use-tbaa-in-sched-mi=0 -post-RA-scheduler=0 -mcpu=ppc64 < %s | FileCheck %s
 
 ; REQUIRES: asserts
 ; -misched=shuffle is NDEBUG only!

Modified: llvm/trunk/test/CodeGen/SystemZ/alias-01.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/alias-01.ll?rev=206093&r1=206092&r2=206093&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/alias-01.ll (original)
+++ llvm/trunk/test/CodeGen/SystemZ/alias-01.ll Fri Apr 11 20:26:00 2014
@@ -2,9 +2,6 @@
 ;
 ; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
 
-; The use of TBAA in CodeGen has been temporarily disabled pending correctness fixes.
-; XFAIL: *
-
 ; Check that there are no spills.
 define void @f1(<16 x i32> *%src1, <16 x float> *%dest) {
 ; CHECK-LABEL: f1: