[llvm] 56e6eb7 - [AArch64][GlobalISel] Make G_UBFX/G_SBFX legalization check for constants

[Jessica Paquette via llvm-commits]

Author: Jessica Paquette
Date: 2021-03-24T13:58:27-07:00
New Revision: 56e6eb797599b3da0cf22a4e2cd293b76cb08c60

URL: https://github.com/llvm/llvm-project/commit/56e6eb797599b3da0cf22a4e2cd293b76cb08c60
DIFF: https://github.com/llvm/llvm-project/commit/56e6eb797599b3da0cf22a4e2cd293b76cb08c60.diff

LOG: [AArch64][GlobalISel] Make G_UBFX/G_SBFX legalization check for constants

The original rule just checked the type, but this is actually only legal if
it has a constant.

Differential Revision: https://reviews.llvm.org/D99298

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
    llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index 8098fba4dc5a..0190ca3c883c 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -702,7 +702,8 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
 
   getActionDefinitionsBuilder({G_FSHL, G_FSHR}).lower();
 
-  getActionDefinitionsBuilder({G_SBFX, G_UBFX}).legalFor({s32, s64});
+  getActionDefinitionsBuilder({G_SBFX, G_UBFX}).customFor({s32, s64});
+
   computeTables();
   verify(*ST.getInstrInfo());
 }
@@ -729,6 +730,9 @@ bool AArch64LegalizerInfo::legalizeCustom(LegalizerHelper &Helper,
     return legalizeSmallCMGlobalValue(MI, MRI, MIRBuilder, Observer);
   case TargetOpcode::G_TRUNC:
     return legalizeVectorTrunc(MI, Helper);
+  case TargetOpcode::G_SBFX:
+  case TargetOpcode::G_UBFX:
+    return legalizeBitfieldExtract(MI, MRI, Helper);
   }
 
   llvm_unreachable("expected switch to return");
@@ -948,3 +952,11 @@ bool AArch64LegalizerInfo::legalizeVaArg(MachineInstr &MI,
   MI.eraseFromParent();
   return true;
 }
+
+bool AArch64LegalizerInfo::legalizeBitfieldExtract(
+    MachineInstr &MI, MachineRegisterInfo &MRI, LegalizerHelper &Helper) const {
+  // Only legal if we can select immediate forms.
+  // TODO: Lower this otherwise.
+  return getConstantVRegValWithLookThrough(MI.getOperand(2).getReg(), MRI) &&
+         getConstantVRegValWithLookThrough(MI.getOperand(3).getReg(), MRI);
+}

diff  --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h
index 8217e37c8512..24c63d7da2ac 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.h
@@ -47,6 +47,8 @@ class AArch64LegalizerInfo : public LegalizerInfo {
                                   MachineIRBuilder &MIRBuilder,
                                   GISelChangeObserver &Observer) const;
   bool legalizeVectorTrunc(MachineInstr &MI, LegalizerHelper &Helper) const;
+  bool legalizeBitfieldExtract(MachineInstr &MI, MachineRegisterInfo &MRI,
+                               LegalizerHelper &Helper) const;
   const AArch64Subtarget *ST;
 };
 } // End llvm namespace.