From 84575f1695d661b89ff246b214ae4b88ca253cfc Mon Sep 17 00:00:00 2001
From: Lucas Steuernagel <38472950+LucasSte@users.noreply.github.com>
Date: Sat, 16 Dec 2023 00:56:02 -0300
Subject: [PATCH] [SOL] Remove `neg` and change the semantics of `sub` (#73)

Following the alterations made in solana-labs/rbpf#489, this PR removes the neg instructions and changes the semantics of sub when one of the operands is an immediate.

sub r1, 2 now means r1 = 2 - r1, instead of r1 = r1 - 2.
neg r1 is represented as r1 = 0  - r1.

This is the second task in solana-labs/solana#34250.
---
 llvm/lib/Target/SBF/SBFInstrInfo.td           | 40 ++++++++--
 llvm/lib/Target/SBF/SBFSubtarget.cpp          |  7 +-
 llvm/lib/Target/SBF/SBFSubtarget.h            |  9 ++-
 .../CodeGen/SBF/sub_reversed_immediate.ll     | 79 +++++++++++++++++++
 4 files changed, 125 insertions(+), 10 deletions(-)
 create mode 100644 llvm/test/CodeGen/SBF/sub_reversed_immediate.ll

diff --git a/llvm/lib/Target/SBF/SBFInstrInfo.td b/llvm/lib/Target/SBF/SBFInstrInfo.td
index 41a66c375408a9..c91a7fbe9bed50 100644
--- a/llvm/lib/Target/SBF/SBFInstrInfo.td
+++ b/llvm/lib/Target/SBF/SBFInstrInfo.td
@@ -54,6 +54,8 @@ def SBFIsBigEndian    : Predicate<"!CurDAG->getDataLayout().isLittleEndian()">;
 def SBFHasALU32 : Predicate<"Subtarget->getHasAlu32()">;
 def SBFNoALU32 : Predicate<"!Subtarget->getHasAlu32()">;
 def SBFSubtargetSolana : Predicate<"Subtarget->isSolana()">;
+def SBFv2 : Predicate<"Subtarget->isSBFv2()">;
+def NoSBFv2 : Predicate<"!Subtarget->isSBFv2()">;
 
 def brtarget : Operand<OtherVT> {
   let PrintMethod = "printBrTargetOperand";
@@ -263,7 +265,7 @@ class ALU_RR<SBFOpClass Class, SBFArithOp Opc,
   let SBFClass = Class;
 }
 
-multiclass ALU<SBFArithOp Opc, string Mnemonic, SDNode OpNode> {
+multiclass ALU<SBFArithOp Opc, string Mnemonic, SDNode OpNode, bit UseImmPat = 1> {
   def _rr : ALU_RR<SBF_ALU64, Opc,
                    (outs GPR:$dst),
                    (ins GPR:$src2, GPR:$src),
@@ -273,7 +275,9 @@ multiclass ALU<SBFArithOp Opc, string Mnemonic, SDNode OpNode> {
                    (outs GPR:$dst),
                    (ins GPR:$src2, i64imm:$imm),
                    Mnemonic # "64 $dst, $imm",
-                   [(set GPR:$dst, (OpNode GPR:$src2, i64immSExt32:$imm))]>;
+                   !if(UseImmPat,
+                       [(set GPR:$dst,
+                            (OpNode GPR:$src2, i64immSExt32:$imm))], [])>;
   def _rr_32 : ALU_RR<SBF_ALU, Opc,
                    (outs GPR32:$dst),
                    (ins GPR32:$src2, GPR32:$src),
@@ -283,13 +287,15 @@ multiclass ALU<SBFArithOp Opc, string Mnemonic, SDNode OpNode> {
                    (outs GPR32:$dst),
                    (ins GPR32:$src2, i32imm:$imm),
                    Mnemonic # "32 $dst, $imm",
-                   [(set GPR32:$dst, (OpNode GPR32:$src2, i32immSExt32:$imm))]>;
+                   !if(UseImmPat,
+                       [(set GPR32:$dst,
+                             (OpNode GPR32:$src2, i32immSExt32:$imm))], [])>;
 }
 
 let Constraints = "$dst = $src2" in {
     let isAsCheapAsAMove = 1 in {
         defm ADD : ALU<SBF_ADD, "add", add>;
-        defm SUB : ALU<SBF_SUB, "sub", sub>;
+        defm SUB : ALU<SBF_SUB, "sub", sub, 0>;
         defm OR  : ALU<SBF_OR, "or", or>;
         defm AND : ALU<SBF_AND, "and", and>;
         defm SLL : ALU<SBF_LSH, "lsh", shl>;
@@ -306,6 +312,19 @@ let Constraints = "$dst = $src2" in {
     }
 }
 
+// Special case for SBFv2
+// In SBFv1, `sub reg, imm` is interpreted as reg = reg - imm,
+// but in SBFv2 it means reg = imm - reg
+def : Pat<(sub GPR:$src, i64immSExt32:$imm),
+          (SUB_ri GPR:$src, i64immSExt32:$imm)>, Requires<[NoSBFv2]>;
+def : Pat<(sub GPR32:$src, i32immSExt32:$imm),
+          (SUB_ri_32 GPR32:$src, i32immSExt32:$imm)>, Requires<[NoSBFv2]>;
+
+def : Pat<(sub i64immSExt32:$imm, GPR:$src),
+          (SUB_ri GPR:$src, i64immSExt32:$imm)>, Requires<[SBFv2]>;
+def : Pat<(sub i32immSExt32:$imm, GPR32:$src),
+          (SUB_ri_32 GPR32:$src, i32immSExt32:$imm)>, Requires<[SBFv2]>;
+
 class NEG_RR<SBFOpClass Class, SBFArithOp Opc,
              dag outs, dag ins, string asmstr, list<dag> pattern>
     : TYPE_ALU_JMP<Opc.Value, 0, outs, ins, asmstr, pattern> {
@@ -318,12 +337,21 @@ class NEG_RR<SBFOpClass Class, SBFArithOp Opc,
 let Constraints = "$dst = $src", isAsCheapAsAMove = 1 in {
   def NEG_64: NEG_RR<SBF_ALU64, SBF_NEG, (outs GPR:$dst), (ins GPR:$src),
                      "neg64 $dst",
-                     [(set GPR:$dst, (ineg i64:$src))]>;
+                     []>;
   def NEG_32: NEG_RR<SBF_ALU, SBF_NEG, (outs GPR32:$dst), (ins GPR32:$src),
                      "neg32 $dst",
-                     [(set GPR32:$dst, (ineg i32:$src))]>;
+                     []>;
 }
 
+// Instruction `neg` exists on SBFv1, but not on SBFv2
+// In SBFv2, the negate operation is done with a subtraction
+def : Pat<(ineg i64:$src), (NEG_64 GPR:$src)>, Requires<[NoSBFv2]>;
+def : Pat<(ineg i32:$src), (NEG_32 GPR32:$src)>, Requires<[NoSBFv2]>;
+
+def : Pat<(ineg i64:$src), (SUB_ri GPR:$src, 0)>, Requires<[SBFv2]>;
+def : Pat<(ineg i32:$src), (SUB_ri_32 GPR32:$src, 0)>, Requires<[SBFv2]>;
+
+
 class LD_IMM64<bits<4> Pseudo, string Mnemonic>
     : TYPE_LD_ST<SBF_IMM.Value, SBF_DW.Value,
                  (outs GPR:$dst),
diff --git a/llvm/lib/Target/SBF/SBFSubtarget.cpp b/llvm/lib/Target/SBF/SBFSubtarget.cpp
index e49f6a31c7ba11..deb57c2d539ae7 100644
--- a/llvm/lib/Target/SBF/SBFSubtarget.cpp
+++ b/llvm/lib/Target/SBF/SBFSubtarget.cpp
@@ -42,6 +42,7 @@ void SBFSubtarget::initializeEnvironment(const Triple &TT) {
   HasDynamicFrames = false;
   HasSdiv = false;
   UseDwarfRIS = false;
+  IsSBFv2 = false;
 }
 
 void SBFSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
@@ -64,8 +65,10 @@ void SBFSubtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
     HasAlu32 = true;
   }
 
-  if (CPU == "sbfv2" && !HasDynamicFrames) {
-    report_fatal_error("sbfv2 requires dynamic-frames\n", false);
+  if (CPU == "sbfv2") {
+    IsSBFv2 = true;
+    if (!HasDynamicFrames)
+      report_fatal_error("sbfv2 requires dynamic-frames\n", false);
   }
 }
 
diff --git a/llvm/lib/Target/SBF/SBFSubtarget.h b/llvm/lib/Target/SBF/SBFSubtarget.h
index 2334bbb1bb89b9..613e0168f45c3a 100644
--- a/llvm/lib/Target/SBF/SBFSubtarget.h
+++ b/llvm/lib/Target/SBF/SBFSubtarget.h
@@ -72,13 +72,17 @@ class SBFSubtarget : public SBFGenSubtargetInfo {
   // whether we should enable MCAsmInfo DwarfUsesRelocationsAcrossSections
   bool UseDwarfRIS;
 
+  // whether we are targeting SBFv2
+  bool IsSBFv2;
+
 public:
   // This constructor initializes the data members to match that
   // of the specified triple.
   SBFSubtarget(const Triple &TT, const std::string &CPU, const std::string &FS,
                const TargetMachine &TM);
 
-  SBFSubtarget &initializeSubtargetDependencies(const Triple &TT, StringRef CPU, StringRef FS);
+  SBFSubtarget &initializeSubtargetDependencies(const Triple &TT, StringRef CPU,
+                                                StringRef FS);
 
   // ParseSubtargetFeatures - Parses features string setting specified
   // subtarget options.  Definition of function is auto generated by tblgen.
@@ -90,6 +94,7 @@ class SBFSubtarget : public SBFGenSubtargetInfo {
   bool getHasDynamicFrames() const { return HasDynamicFrames; }
   bool getHasSdiv() const { return HasSdiv; }
   bool getUseDwarfRIS() const { return UseDwarfRIS; }
+  bool isSBFv2() const { return IsSBFv2; }
 
   const SBFInstrInfo *getInstrInfo() const override { return &InstrInfo; }
   const SBFFrameLowering *getFrameLowering() const override {
@@ -105,6 +110,6 @@ class SBFSubtarget : public SBFGenSubtargetInfo {
     return &InstrInfo.getRegisterInfo();
   }
 };
-} // End llvm namespace
+} // namespace llvm
 
 #endif
diff --git a/llvm/test/CodeGen/SBF/sub_reversed_immediate.ll b/llvm/test/CodeGen/SBF/sub_reversed_immediate.ll
new file mode 100644
index 00000000000000..8040eb767b728e
--- /dev/null
+++ b/llvm/test/CodeGen/SBF/sub_reversed_immediate.ll
@@ -0,0 +1,79 @@
+; RUN: llc < %s -march=sbf -mattr=+alu32 | FileCheck  --check-prefix=CHECK-v1 %s
+; RUN: llc < %s -march=sbf -mattr=+alu32 -mcpu=sbfv2 | FileCheck  --check-prefix=CHECK-v2 %s
+
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i64 @sub_imm_minus_reg_64(i64 %a) #0 {
+entry:
+; CHECK-LABEL: sub_imm_minus_reg_64:
+  %sub = sub nsw i64 50, %a
+
+; CHECK-v1: mov64 r{{[0-9]+}}, 50
+; CHECK-v1: sub64 r{{[0-9]+}}, r{{[0-9]+}}
+
+; CHECK-v2: sub64 r{{[0-9]+}}, 50
+  ret i64 %sub
+}
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i64 @sub_reg_minus_imm_64(i64 %a) #0 {
+entry:
+; CHECK-LABEL: sub_reg_minus_imm_64:
+  %t = sub nsw i64 %a, 50
+; CHECK-v1: add64 r{{[0-9]+}}, -50
+
+; CHECK-v2: add64 r{{[0-9]+}}, -50
+  ret i64 %t
+}
+
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i32 @sub_imm_minus_reg_32(i32 %a) #0 {
+entry:
+; CHECK-LABEL: sub_imm_minus_reg_32:
+  %sub = sub nsw i32 50, %a
+
+; CHECK-v1: mov32 w{{[0-9]+}}, 50
+; CHECK-v1: sub32 w{{[0-9]+}}, w{{[0-9]+}}
+
+; CHECK-v2: sub32 w{{[0-9]+}}, 50
+
+  ret i32 %sub
+}
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i32 @sub_reg_minus_imm_32(i32 %a) #0 {
+entry:
+; CHECK-LABEL: sub_reg_minus_imm_32:
+  %t = sub nsw i32 %a, 50
+
+; CHECK-v1: add32 w{{[0-9]+}}, -50
+
+; CHECK-v2: add32 w{{[0-9]+}}, -50
+  ret i32 %t
+}
+
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i64 @neg_64(i64 %a) #0 {
+entry:
+; CHECK-LABEL: neg_64:
+  %sub = sub nsw i64 0, %a
+
+; CHECK-v1: neg64 r{{[0-9]+}}
+; CHECK-v2: sub64 r{{[0-9]+}}, 0
+
+  ret i64 %sub
+}
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i32 @neg_32(i32 %a) #0 {
+entry:
+; CHECK-LABEL: neg_32:
+  %sub = sub nsw i32 0, %a
+
+; CHECK-v1: neg32 w{{[0-9]+}}
+; CHECK-v2: sub32 w{{[0-9]+}}, 0
+
+  ret i32 %sub
+}