1 files changed, 41 insertions, 17 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
index 647fae904d39..79bcf5e8cd30 100644
--- a/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
+++ b/llvm/lib/Target/AMDGPU/SIShrinkInstructions.cpp
@@ -45,7 +45,6 @@ public:
   bool isKImmOperand(const MachineOperand &Src) const;
   bool isKUImmOperand(const MachineOperand &Src) const;
   bool isKImmOrKUImmOperand(const MachineOperand &Src, bool &IsUnsigned) const;
-  bool isReverseInlineImm(const MachineOperand &Src, int32_t &ReverseImm) const;
   void copyExtraImplicitOps(MachineInstr &NewMI, MachineInstr &MI) const;
   void shrinkScalarCompare(MachineInstr &MI) const;
   void shrinkMIMG(MachineInstr &MI) const;
@@ -183,15 +182,36 @@ bool SIShrinkInstructions::isKImmOrKUImmOperand(const MachineOperand &Src,
   return false;
 }
 
-/// \returns true if the constant in \p Src should be replaced with a bitreverse
-/// of an inline immediate.
-bool SIShrinkInstructions::isReverseInlineImm(const MachineOperand &Src,
-                                              int32_t &ReverseImm) const {
-  if (!isInt<32>(Src.getImm()) || TII->isInlineConstant(Src))
-    return false;
+/// \returns the opcode of an instruction a move immediate of the constant \p
+/// Src can be replaced with if the constant is replaced with \p ModifiedImm.
+/// i.e.
+///
+/// If the bitreverse of a constant is an inline immediate, reverse the
+/// immediate and return the bitreverse opcode.
+///
+/// If the bitwise negation of a constant is an inline immediate, reverse the
+/// immediate and return the bitwise not opcode.
+static unsigned canModifyToInlineImmOp32(const SIInstrInfo *TII,
+                                         const MachineOperand &Src,
+                                         int32_t &ModifiedImm, bool Scalar) {
+  if (TII->isInlineConstant(Src))
+    return 0;
+  int32_t SrcImm = static_cast<int32_t>(Src.getImm());
+
+  if (!Scalar) {
+    // We could handle the scalar case with here, but we would need to check
+    // that SCC is not live as S_NOT_B32 clobbers it. It's probably not worth
+    // it, as the reasonable values are already covered by s_movk_i32.
+    ModifiedImm = ~SrcImm;
+    if (TII->isInlineConstant(APInt(32, ModifiedImm)))
+      return AMDGPU::V_NOT_B32_e32;
+  }
+
+  ModifiedImm = reverseBits<int32_t>(SrcImm);
+  if (TII->isInlineConstant(APInt(32, ModifiedImm)))
+    return Scalar ? AMDGPU::S_BREV_B32 : AMDGPU::V_BFREV_B32_e32;
 
-  ReverseImm = reverseBits<int32_t>(static_cast<int32_t>(Src.getImm()));
-  return ReverseImm >= -16 && ReverseImm <= 64;
+  return 0;
 }
 
 /// Copy implicit register operands from specified instruction to this
@@ -801,10 +821,12 @@ bool SIShrinkInstructions::runOnMachineFunction(MachineFunction &MF) {
         // XXX - not exactly a check for post-regalloc run.
         MachineOperand &Src = MI.getOperand(1);
         if (Src.isImm() && MI.getOperand(0).getReg().isPhysical()) {
-          int32_t ReverseImm;
-          if (isReverseInlineImm(Src, ReverseImm)) {
-            MI.setDesc(TII->get(AMDGPU::V_BFREV_B32_e32));
-            Src.setImm(ReverseImm);
+          int32_t ModImm;
+          unsigned ModOpcode =
+              canModifyToInlineImmOp32(TII, Src, ModImm, /*Scalar=*/false);
+          if (ModOpcode != 0) {
+            MI.setDesc(TII->get(ModOpcode));
+            Src.setImm(static_cast<int64_t>(ModImm));
             continue;
           }
         }
@@ -863,13 +885,15 @@ bool SIShrinkInstructions::runOnMachineFunction(MachineFunction &MF) {
         MachineOperand &Src = MI.getOperand(1);
 
         if (Src.isImm() && Dst.getReg().isPhysical()) {
-          int32_t ReverseImm;
+          unsigned ModOpc;
+          int32_t ModImm;
           if (isKImmOperand(Src)) {
             MI.setDesc(TII->get(AMDGPU::S_MOVK_I32));
             Src.setImm(SignExtend64(Src.getImm(), 32));
-          } else if (isReverseInlineImm(Src, ReverseImm)) {
-            MI.setDesc(TII->get(AMDGPU::S_BREV_B32));
-            Src.setImm(ReverseImm);
+          } else if ((ModOpc = canModifyToInlineImmOp32(TII, Src, ModImm,
+                                                        /*Scalar=*/true))) {
+            MI.setDesc(TII->get(ModOpc));
+            Src.setImm(static_cast<int64_t>(ModImm));
           }
         }