[PATCH] D34743: [AArch64] AArch64CondBrTuningPass generates wrong branch instructions

[Alexandros Lamprineas via Phabricator via llvm-commits]

labrinea created this revision.
Herald added subscribers: kristof.beyls, javed.absar, rengolin, aemerson.

Some conditional branch instructions generated by this pass are checking the wrong condition code. The instructions TBZ and TBNZ are transformed into B.GE and B.LT instead of B.PL and B.MI respectively. They should only be checking the Negative bit.


https://reviews.llvm.org/D34743

Files:
  lib/Target/AArch64/AArch64CondBrTuning.cpp
  test/CodeGen/AArch64/cond-br-tuning.ll


Index: test/CodeGen/AArch64/cond-br-tuning.ll
===================================================================
--- test/CodeGen/AArch64/cond-br-tuning.ll
+++ test/CodeGen/AArch64/cond-br-tuning.ll
@@ -83,7 +83,7 @@
 
 ; CHECK-LABEL: test_add_tbz:
 ; CHECK: adds
-; CHECK: b.ge
+; CHECK: b.pl
 ; CHECK: ret
 define void @test_add_tbz(i32 %a, i32 %b, i32* %ptr) {
 entry:
@@ -99,7 +99,7 @@
 
 ; CHECK-LABEL: test_subs_tbz:
 ; CHECK: subs
-; CHECK: b.ge
+; CHECK: b.pl
 ; CHECK: ret
 define void @test_subs_tbz(i32 %a, i32 %b, i32* %ptr) {
 entry:
@@ -115,7 +115,7 @@
 
 ; CHECK-LABEL: test_add_tbnz
 ; CHECK: adds
-; CHECK: b.lt
+; CHECK: b.mi
 ; CHECK: ret
 define void @test_add_tbnz(i32 %a, i32 %b, i32* %ptr) {
 entry:
@@ -131,7 +131,7 @@
 
 ; CHECK-LABEL: test_subs_tbnz
 ; CHECK: subs
-; CHECK: b.lt
+; CHECK: b.mi
 ; CHECK: ret
 define void @test_subs_tbnz(i32 %a, i32 %b, i32* %ptr) {
 entry:
Index: lib/Target/AArch64/AArch64CondBrTuning.cpp
===================================================================
--- lib/Target/AArch64/AArch64CondBrTuning.cpp
+++ lib/Target/AArch64/AArch64CondBrTuning.cpp
@@ -129,11 +129,11 @@
     break;
   case AArch64::TBZW:
   case AArch64::TBZX:
-    CC = AArch64CC::GE;
+    CC = AArch64CC::PL;
     break;
   case AArch64::TBNZW:
   case AArch64::TBNZX:
-    CC = AArch64CC::LT;
+    CC = AArch64CC::MI;
     break;
   }
   return BuildMI(*MI.getParent(), MI, MI.getDebugLoc(), TII->get(AArch64::Bcc))


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