[PATCH] D23382: AMDGPU: Fix not estimating MBB operand sizes correctly

[Matt Arsenault via llvm-commits]

arsenm created this revision.
arsenm added a reviewer: tstellarAMD.
arsenm added a subscriber: llvm-commits.
Herald added subscribers: kzhuravl, arsenm.

https://reviews.llvm.org/D23382

Files:
  lib/Target/AMDGPU/SIInstrInfo.cpp
  lib/Target/AMDGPU/SIInstrInfo.h

Index: lib/Target/AMDGPU/SIInstrInfo.h
===================================================================
--- lib/Target/AMDGPU/SIInstrInfo.h
+++ lib/Target/AMDGPU/SIInstrInfo.h
@@ -384,6 +384,12 @@
   bool isInlineConstant(const MachineOperand &MO, unsigned OpSize) const;
   bool isLiteralConstant(const MachineOperand &MO, unsigned OpSize) const;
 
+  // Returns true if this operand could potentially require a 32-bit literal
+  // operand, but not necessarily. A FrameIndex for example could resolve to an
+  // inline immediate value that will not require an additional 4-bytes; this
+  // assumes that it will.
+  bool isLiteralConstantLike(const MachineOperand &MO, unsigned OpSize) const;
+
   bool isImmOperandLegal(const MachineInstr &MI, unsigned OpNo,
                          const MachineOperand &MO) const;
 
Index: lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- lib/Target/AMDGPU/SIInstrInfo.cpp
+++ lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -1515,6 +1515,24 @@
   return MO.isImm() && !isInlineConstant(MO, OpSize);
 }
 
+bool SIInstrInfo::isLiteralConstantLike(const MachineOperand &MO,
+                                        unsigned OpSize) const {
+  switch (MO.getType()) {
+  case MachineOperand::MO_Register:
+    return false;
+  case MachineOperand::MO_Immediate:
+    return !isInlineConstant(MO, OpSize);
+  case MachineOperand::MO_FrameIndex:
+  case MachineOperand::MO_MachineBasicBlock:
+  case MachineOperand::MO_ExternalSymbol:
+  case MachineOperand::MO_GlobalAddress:
+  case MachineOperand::MO_MCSymbol:
+    return true;
+  default:
+    llvm_unreachable("unexpected operand type");
+  }
+}
+
 static bool compareMachineOp(const MachineOperand &Op0,
                              const MachineOperand &Op1) {
   if (Op0.getType() != Op1.getType())
@@ -3156,14 +3174,14 @@
     if (Src0Idx == -1)
       return 4; // No operands.
 
-    if (isLiteralConstant(MI.getOperand(Src0Idx), getOpSize(MI, Src0Idx)))
+    if (isLiteralConstantLike(MI.getOperand(Src0Idx), getOpSize(MI, Src0Idx)))
       return 8;
 
     int Src1Idx = AMDGPU::getNamedOperandIdx(Opc, AMDGPU::OpName::src1);
     if (Src1Idx == -1)
       return 4;
 
-    if (isLiteralConstant(MI.getOperand(Src1Idx), getOpSize(MI, Src1Idx)))
+    if (isLiteralConstantLike(MI.getOperand(Src1Idx), getOpSize(MI, Src1Idx)))
       return 8;
 
     return 4;


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