[clang] [llvm] [AIX] support builtin_cpu_is() for aix (PR #80069)

[Amy Kwan via llvm-commits]

================
@@ -16542,12 +16542,64 @@ Value *CodeGenFunction::EmitPPCBuiltinExpr(unsigned BuiltinID,
 
   Intrinsic::ID ID = Intrinsic::not_intrinsic;
 
+  // The lambda function converts builtin_cpu_is function into directly
+  // returning false or true, or it gets and checks the information from the
+  // kernel variable _system_configuration for AIX OS.
+
+#include "llvm/TargetParser/PPCTargetParser.def"
+  auto ConvBuiltinCpu = [&](unsigned SupportMagic, unsigned FieldIdx,
+                            unsigned CompOp, unsigned OpValue) -> Value * {
+    if (SupportMagic == AIX_BUILTIN_PPC_FALSE)
+      return llvm::ConstantInt::getFalse(ConvertType(E->getType()));
+
+    if (SupportMagic == AIX_BUILTIN_PPC_TRUE)
+      return llvm::ConstantInt::getTrue(ConvertType(E->getType()));
+
+    assert(SupportMagic <= SYS_CONF && "Invalid value for SupportMagic.");
+    llvm::Type *STy = llvm::StructType::get(PPC_SYSTEMCONFIG_TYPE);
+
+    llvm::Constant *SysConf =
+        CGM.CreateRuntimeVariable(STy, "_system_configuration");
+
+    // Grab the appropriate field from _system_configuration.
+    llvm::Value *Idxs[] = {ConstantInt::get(Int32Ty, 0),
+                           ConstantInt::get(Int32Ty, FieldIdx)};
+
+    llvm::Value *FieldValue = Builder.CreateGEP(STy, SysConf, Idxs);
+    FieldValue = Builder.CreateAlignedLoad(Int32Ty, FieldValue,
+                                           CharUnits::fromQuantity(4));
+
+    assert((CompOp == COMP_EQ) && "Only equal comparisons are supported!");
+
+    assert(FieldValue->getType()->isIntegerTy(32) &&
+           "Only supports 32-bit integer in the GetOpRes.");
+
+    return Builder.CreateICmp(ICmpInst::ICMP_EQ, FieldValue,
+                              ConstantInt::get(Int32Ty, OpValue));
+  };
+
   switch (BuiltinID) {
   default: return nullptr;
 
   case Builtin::BI__builtin_cpu_is: {
     const Expr *CPUExpr = E->getArg(0)->IgnoreParenCasts();
     StringRef CPUStr = cast<clang::StringLiteral>(CPUExpr)->getString();
+    llvm::Triple Triple = getTarget().getTriple();
+
+    if (Triple.isOSAIX()) {
+      unsigned IsCpuSupport, FieldIdx, CompareOp, CpuIdValue;
+      typedef std::tuple<unsigned, unsigned, unsigned, unsigned> CPUType;
+      std::tie(IsCpuSupport, FieldIdx, CompareOp, CpuIdValue) =
+          static_cast<CPUType>(StringSwitch<CPUType>(CPUStr)
+#define PPC_AIX_CPU(NAME, SUPPORT_MAGIC, INDEX, COMPARE_OP, VALUE)             \
+  .Case(NAME, {SUPPORT_MAGIC, INDEX, COMPARE_OP, VALUE})
+#include "llvm/TargetParser/PPCTargetParser.def"
+          );
+      return ConvBuiltinCpu(IsCpuSupport, FieldIdx, CompareOp, CpuIdValue);
+    }
+
+    assert(Triple.isOSLinux() && "Triple for AIX OS has already been checked; "
+                                 "it must be Linux OS here.");
----------------
amy-kwan wrote:

Comment should be updated to something like:
```
__builtin_cpu_is() is only supported for AIX and Linux.
```
For here and on line 915 on `PPC.cpp`.


https://github.com/llvm/llvm-project/pull/80069