[PATCH] D105754: [PowerPC] Fix L[D|W]ARX Implementation

[Albion Fung via Phabricator via cfe-commits]

Conanap created this revision.
Herald added subscribers: shchenz, kbarton, hiraditya, nemanjai.
Conanap requested review of this revision.
Herald added projects: clang, LLVM.
Herald added subscribers: llvm-commits, cfe-commits.

LDARX and LWARX sometimes gets optimized out by the compiler
when it is critical to the correctness of the code. This inline asm generation
ensures that it preserved.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105754

Files:
  clang/lib/CodeGen/CGBuiltin.cpp
  llvm/include/llvm/IR/IntrinsicsPowerPC.td
  llvm/lib/Target/PowerPC/PPCInstr64Bit.td
  llvm/lib/Target/PowerPC/PPCInstrInfo.td


Index: llvm/lib/Target/PowerPC/PPCInstrInfo.td
===================================================================
--- llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -5412,7 +5412,5 @@
 def : Pat<(i64 (bitreverse i64:$A)),
   (OR8 (RLDICR DWBytes7654.DWord, 32, 31), DWBytes3210.DWord)>;
 
-def : Pat<(int_ppc_lwarx ForceXForm:$dst),
-          (LWARX ForceXForm:$dst)>;
 def : Pat<(int_ppc_stwcx ForceXForm:$dst, gprc:$A),
           (STWCX gprc:$A, ForceXForm:$dst)>;
Index: llvm/lib/Target/PowerPC/PPCInstr64Bit.td
===================================================================
--- llvm/lib/Target/PowerPC/PPCInstr64Bit.td
+++ llvm/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -1723,5 +1723,3 @@
 
 def : Pat<(int_ppc_stdcx ForceXForm:$dst, g8rc:$A),
           (STDCX g8rc:$A, ForceXForm:$dst)>;
-def : Pat<(int_ppc_ldarx ForceXForm:$dst),
-          (LDARX ForceXForm:$dst)>;
Index: llvm/include/llvm/IR/IntrinsicsPowerPC.td
===================================================================
--- llvm/include/llvm/IR/IntrinsicsPowerPC.td
+++ llvm/include/llvm/IR/IntrinsicsPowerPC.td
@@ -1529,9 +1529,5 @@
   def int_ppc_stwcx : GCCBuiltin<"__builtin_ppc_stwcx">,
                       Intrinsic<[llvm_i32_ty], [llvm_ptr_ty, llvm_i32_ty],
                                 [IntrWriteMem]>;
-  def int_ppc_lwarx : GCCBuiltin<"__builtin_ppc_lwarx">,
-                      Intrinsic<[llvm_i32_ty], [llvm_ptr_ty], [IntrNoMem]>;
-  def int_ppc_ldarx : GCCBuiltin<"__builtin_ppc_ldarx">,
-                      Intrinsic<[llvm_i64_ty], [llvm_ptr_ty], [IntrNoMem]>;
 }
 
Index: clang/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- clang/lib/CodeGen/CGBuiltin.cpp
+++ clang/lib/CodeGen/CGBuiltin.cpp
@@ -994,6 +994,44 @@
       ShiftedByte, llvm::ConstantInt::get(CGF.Int8Ty, 1), "bittest.res");
 }
 
+static llvm::Value *emitLoadReserveIntrinsic(CodeGenFunction &CGF,
+                                             unsigned BuiltinID,
+                                             const CallExpr *E) {
+  Value *addr = CGF.EmitScalarExpr(E->getArg(0));
+
+  SmallString<64> Asm;
+  raw_svector_ostream AsmOS(Asm);
+  llvm::IntegerType *RetType = CGF.Int32Ty;
+
+  switch (BuiltinID) {
+  case clang::PPC::BI__builtin_ppc_ldarx:
+    AsmOS << "ldarx ";
+    RetType = CGF.Int64Ty;
+    break;
+  case clang::PPC::BI__builtin_ppc_lwarx:
+    AsmOS << "lwarx ";
+    RetType = CGF.Int32Ty;
+    break;
+  }
+
+  AsmOS << "$0, $1";
+
+  std::string Constraints = "=r,*Z,~{memory}";
+  std::string MachineClobbers = CGF.getTarget().getClobbers();
+  if (!MachineClobbers.empty()) {
+    Constraints += ',';
+    Constraints += MachineClobbers;
+  }
+
+  llvm::Type *IntPtrType = RetType->getPointerTo();
+  llvm::FunctionType *FTy =
+      llvm::FunctionType::get(RetType, {IntPtrType}, false);
+
+  llvm::InlineAsm *IA =
+      llvm::InlineAsm::get(FTy, Asm, Constraints, /*hasSideEffects=*/true);
+  return CGF.Builder.CreateCall(IA, {addr});
+}
+
 namespace {
 enum class MSVCSetJmpKind {
   _setjmpex,
@@ -5103,6 +5141,9 @@
                                                      Str.getPointer(), Zeros);
     return RValue::get(Ptr);
   }
+  case clang::PPC::BI__builtin_ppc_ldarx:
+  case clang::PPC::BI__builtin_ppc_lwarx:
+    return RValue::get(emitLoadReserveIntrinsic(*this, BuiltinID, E));
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit


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