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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206093 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index c8328ad4911f573ba9d2dffd1875594338142734..7fba88a2ada8e69c93e518c34d8f970c20ee499a 100644 (file)
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -45,14 +45,8 @@ static cl::opt<bool> EnableAASchedMI("enable-aa-sched-mi", cl::Hidden,
     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,

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 9c33640a514cf053fa7e9d3059cde67020fc7b01..160b92f38981f34e6576c615beb4e3c408cce214 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -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

diff --git a/test/CodeGen/PowerPC/aa-tbaa.ll b/test/CodeGen/PowerPC/aa-tbaa.ll
index d7f80fa48cc1fc6486c1bcd08b7c362d86b71ba2..1939841f1f7ed961b8467b04226ca9596d6007c1 100644 (file)
--- a/test/CodeGen/PowerPC/aa-tbaa.ll
+++ b/test/CodeGen/PowerPC/aa-tbaa.ll
@@ -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!

diff --git a/test/CodeGen/SystemZ/alias-01.ll b/test/CodeGen/SystemZ/alias-01.ll
index dc904816d61bbc350036e7fdaeffaf81e0c9fc8e..8839aade7a0e3d13ab9826e4a78ef07e1390f53e 100644 (file)
--- a/test/CodeGen/SystemZ/alias-01.ll
+++ b/test/CodeGen/SystemZ/alias-01.ll
@@ -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: