R600/SI: Don't shrink instructions whose e32 encoding doesn't exist

v2: modify hasVALU32BitEncoding instead
v3: - add pseudoToMCOpcode helper to AMDGPUInstInfo, which is used by both
      hasVALU32BitEncoding and AMDGPUMCInstLower::lower
    - report an error if a pseudo can't be lowered
llvm-svn: 226188

llvm/lib/Target/R600/AMDGPUInstrInfo.cpp

@@ -341,8 +341,39 @@ int AMDGPUInstrInfo::getMaskedMIMGOp(uint16_t Opcode, unsigned Channels) const {
 // instead.
 namespace llvm {
 namespace AMDGPU {
-int getMCOpcode(uint16_t Opcode, unsigned Gen) {
+static int getMCOpcode(uint16_t Opcode, unsigned Gen) {
   return getMCOpcodeGen(Opcode, (enum Subtarget)Gen);
 }
 }
 }
+
+// This must be kept in sync with the SISubtarget class in SIInstrInfo.td
+enum SISubtarget {
+  SI = 0,
+  VI = 1
+};
+
+enum SISubtarget AMDGPUSubtargetToSISubtarget(unsigned Gen) {
+  switch (Gen) {
+  default:
+    return SI;
+  case AMDGPUSubtarget::VOLCANIC_ISLANDS:
+    return VI;
+  }
+}
+
+int AMDGPUInstrInfo::pseudoToMCOpcode(int Opcode) const {
+  int MCOp = AMDGPU::getMCOpcode(Opcode,
+                        AMDGPUSubtargetToSISubtarget(RI.ST.getGeneration()));
+
+  // -1 means that Opcode is already a native instruction.
+  if (MCOp == -1)
+    return Opcode;
+
+  // (uint16_t)-1 means that Opcode is a pseudo instruction that has
+  // no encoding in the given subtarget generation.
+  if (MCOp == (uint16_t)-1)
+    return -1;
+
+  return MCOp;
+}

llvm/lib/Target/R600/AMDGPUInstrInfo.h

@@ -135,6 +135,11 @@ public:
   bool isRegisterStore(const MachineInstr &MI) const;
   bool isRegisterLoad(const MachineInstr &MI) const;
 
+  /// \brief Return a target-specific opcode if Opcode is a pseudo instruction.
+  /// Return -1 if the target-specific opcode for the pseudo instruction does
+  /// not exist. If Opcode is not a pseudo instruction, this is identity.
+  int pseudoToMCOpcode(int Opcode) const;
+
 //===---------------------------------------------------------------------===//
 // Pure virtual funtions to be implemented by sub-classes.
 //===---------------------------------------------------------------------===//

llvm/lib/Target/R600/AMDGPUMCInstLower.cpp

@@ -22,6 +22,7 @@
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/MC/MCCodeEmitter.h"
 #include "llvm/MC/MCContext.h"
@@ -39,29 +40,17 @@ AMDGPUMCInstLower::AMDGPUMCInstLower(MCContext &ctx, const AMDGPUSubtarget &st):
   Ctx(ctx), ST(st)
 { }
 
-enum AMDGPUMCInstLower::SISubtarget
-AMDGPUMCInstLower::AMDGPUSubtargetToSISubtarget(unsigned Gen) const {
-  switch (Gen) {
-  default:
-    return AMDGPUMCInstLower::SI;
-  case AMDGPUSubtarget::VOLCANIC_ISLANDS:
-    return AMDGPUMCInstLower::VI;
-  }
-}
-
-unsigned AMDGPUMCInstLower::getMCOpcode(unsigned MIOpcode) const {
-
-  int MCOpcode = AMDGPU::getMCOpcode(MIOpcode,
-                              AMDGPUSubtargetToSISubtarget(ST.getGeneration()));
-  if (MCOpcode == -1)
-    MCOpcode = MIOpcode;
-
-  return MCOpcode;
-}
-
 void AMDGPUMCInstLower::lower(const MachineInstr *MI, MCInst &OutMI) const {
 
-  OutMI.setOpcode(getMCOpcode(MI->getOpcode()));
+  int MCOpcode = ST.getInstrInfo()->pseudoToMCOpcode(MI->getOpcode());
+
+  if (MCOpcode == -1) {
+    LLVMContext &C = MI->getParent()->getParent()->getFunction()->getContext();
+    C.emitError("AMDGPUMCInstLower::lower - Pseudo instruction doesn't have "
+                "a target-specific version: " + Twine(MI->getOpcode()));
+  }
+
+  OutMI.setOpcode(MCOpcode);
 
   for (const MachineOperand &MO : MI->explicit_operands()) {
     MCOperand MCOp;

llvm/lib/Target/R600/AMDGPUMCInstLower.h

@@ -19,23 +19,9 @@ class MCContext;
 class MCInst;
 
 class AMDGPUMCInstLower {
-
-  // This must be kept in sync with the SISubtarget class in SIInstrInfo.td
-  enum SISubtarget {
-    SI = 0,
-    VI = 1
-  };
-
   MCContext &Ctx;
   const AMDGPUSubtarget &ST;
 
-  /// Convert a member of the AMDGPUSubtarget::Generation enum to the
-  /// SISubtarget enum.
-  enum SISubtarget AMDGPUSubtargetToSISubtarget(unsigned Gen) const;
-
-  /// Get the MC opcode for this MachineInstr.
-  unsigned getMCOpcode(unsigned MIOpcode) const;
-
 public:
   AMDGPUMCInstLower(MCContext &ctx, const AMDGPUSubtarget &ST);
 

llvm/lib/Target/R600/SIInstrInfo.cpp

@@ -1053,7 +1053,11 @@ bool SIInstrInfo::canFoldOffset(unsigned OffsetSize, unsigned AS) const {
 }
 
 bool SIInstrInfo::hasVALU32BitEncoding(unsigned Opcode) const {
-  return AMDGPU::getVOPe32(Opcode) != -1;
+  int Op32 = AMDGPU::getVOPe32(Opcode);
+  if (Op32 == -1)
+    return false;
+
+  return pseudoToMCOpcode(Op32) != -1;
 }
 
 bool SIInstrInfo::hasModifiers(unsigned Opcode) const {

llvm/lib/Target/R600/SIInstrInfo.h

@@ -325,7 +325,6 @@ namespace AMDGPU {
   int getVOPe32(uint16_t Opcode);
   int getCommuteRev(uint16_t Opcode);
   int getCommuteOrig(uint16_t Opcode);
-  int getMCOpcode(uint16_t Opcode, unsigned Gen);
   int getAddr64Inst(uint16_t Opcode);
   int getAtomicRetOp(uint16_t Opcode);
   int getAtomicNoRetOp(uint16_t Opcode);

llvm/lib/Target/R600/SIInstrInfo.td

@@ -57,7 +57,7 @@ class sopk <bits<5> si, bits<5> vi = si> {
 }
 
 // Execpt for the NONE field, this must be kept in sync with the SISubtarget enum
-// in AMDGPUMCInstLower.h
+// in AMDGPUInstrInfo.cpp
 def SISubtarget {
   int NONE = -1;
   int SI = 0;

llvm/lib/Target/R600/SIShrinkInstructions.cpp

@@ -10,6 +10,7 @@
 //
 
 #include "AMDGPU.h"
+#include "AMDGPUMCInstLower.h"
 #include "AMDGPUSubtarget.h"
 #include "SIInstrInfo.h"
 #include "llvm/ADT/Statistic.h"
@@ -206,13 +207,13 @@ bool SIShrinkInstructions::runOnMachineFunction(MachineFunction &MF) {
           continue;
       }
 
-      int Op32 = AMDGPU::getVOPe32(MI.getOpcode());
-
-      // Op32 could be -1 here if we started with an instruction that had a
+      // getVOPe32 could be -1 here if we started with an instruction that had
       // a 32-bit encoding and then commuted it to an instruction that did not.
-      if (Op32 == -1)
+      if (!TII->hasVALU32BitEncoding(MI.getOpcode()))
         continue;
 
+      int Op32 = AMDGPU::getVOPe32(MI.getOpcode());
+
       if (TII->isVOPC(Op32)) {
         unsigned DstReg = MI.getOperand(0).getReg();
         if (TargetRegisterInfo::isVirtualRegister(DstReg)) {