[llvm] 8807139 - [ARM] Only produce qadd8b under hasV6Ops

[David Green via llvm-commits]

Author: David Green
Date: 2020-04-27T10:13:29+01:00
New Revision: 8807139026b64ac40163bb255dad38a1d8054f08

URL: https://github.com/llvm/llvm-project/commit/8807139026b64ac40163bb255dad38a1d8054f08
DIFF: https://github.com/llvm/llvm-project/commit/8807139026b64ac40163bb255dad38a1d8054f08.diff

LOG: [ARM] Only produce qadd8b under hasV6Ops

When compiling for a arm5te cpu from clang, the +dsp attribute is set.
This meant we could try and generate qadd8 instructions where we would
end up having no pattern. I've changed the condition here to be hasV6Ops
&& hasDSP, which is what other parts of ARMISelLowering seem to use for
similar instructions.

Fixed PR45677.

Differential Revision: https://reviews.llvm.org/D78877

Added: 
    

Modified: 
    llvm/lib/Target/ARM/ARMISelLowering.cpp
    llvm/test/CodeGen/ARM/sadd_sat.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index e9ecc0589350..3e4d798322ae 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -4586,7 +4586,7 @@ SDValue ARMTargetLowering::LowerUnsignedALUO(SDValue Op,
 static SDValue LowerSADDSUBSAT(SDValue Op, SelectionDAG &DAG,
                                const ARMSubtarget *Subtarget) {
   EVT VT = Op.getValueType();
-  if (!Subtarget->hasDSP())
+  if (!Subtarget->hasV6Ops() || !Subtarget->hasDSP())
     return SDValue();
   if (!VT.isSimple())
     return SDValue();

diff  --git a/llvm/test/CodeGen/ARM/sadd_sat.ll b/llvm/test/CodeGen/ARM/sadd_sat.ll
index 386e750ddd1b..9f46364c8ec3 100644
--- a/llvm/test/CodeGen/ARM/sadd_sat.ll
+++ b/llvm/test/CodeGen/ARM/sadd_sat.ll
@@ -4,6 +4,7 @@
 ; RUN: llc < %s -mtriple=thumbv7em-none-eabi | FileCheck %s --check-prefix=CHECK-T2 --check-prefix=CHECK-T2DSP
 ; RUN: llc < %s -mtriple=armv5t-none-eabi | FileCheck %s --check-prefix=CHECK-ARM --check-prefix=CHECK-ARMNODPS
 ; RUN: llc < %s -mtriple=armv5te-none-eabi | FileCheck %s --check-prefix=CHECK-ARM --check-prefix=CHECK-ARMBASEDSP
+; RUN: llc < %s -mtriple=armv5te-none-eabi -mattr=+dsp | FileCheck %s --check-prefix=CHECK-ARM --check-prefix=CHECK-ARMBASEDSP
 ; RUN: llc < %s -mtriple=armv6-none-eabi | FileCheck %s --check-prefix=CHECK-ARM --check-prefix=CHECK-ARMDSP
 
 declare i4 @llvm.sadd.sat.i4(i4, i4)