Index: lib/Sema/SemaChecking.cpp
===================================================================
--- lib/Sema/SemaChecking.cpp
+++ lib/Sema/SemaChecking.cpp
@@ -85,6 +85,10 @@
 #include "llvm/Support/Locale.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/raw_ostream.h"
+
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Module.h"
+
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
@@ -965,15 +969,178 @@
   if (Error != ASTContext::GE_None)
     ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
 
-  // If any arguments are required to be ICE's, check and diagnose.
-  for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
-    // Skip arguments not required to be ICE's.
-    if ((ICEArguments & (1 << ArgNo)) == 0) continue;
+  static bool Once = false;
 
-    llvm::APSInt Result;
-    if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
-      return true;
-    ICEArguments &= ~(1 << ArgNo);
+  if (!Once) {
+    Once = true;
+    unsigned Start = -1;
+    unsigned End = -1;
+    switch (Context.getTargetInfo().getTriple().getArch()) {
+    case llvm::Triple::x86: {
+      Start = X86::LastTIBuiltin + 1;
+      End = X86::LastX86CommonBuiltin;
+      break;
+    }
+    case llvm::Triple::x86_64: {
+      Start = X86::LastTIBuiltin + 1;
+      //Start = X86::FirstX86_64Builtin;
+      End = X86::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::mips:
+    case llvm::Triple::mipsel:
+    case llvm::Triple::mips64:
+    case llvm::Triple::mips64el: {
+      Start = Mips::LastTIBuiltin + 1;
+      End = Mips::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::hexagon: {
+      Start = Hexagon::LastTIBuiltin + 1;
+      End = Hexagon::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::systemz: {
+      Start = SystemZ::LastTIBuiltin + 1;
+      End = SystemZ::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::ppc:
+    case llvm::Triple::ppc64:
+    case llvm::Triple::ppc64le: {
+      Start = PPC::LastTIBuiltin + 1;
+      End = PPC::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_be: {
+      Start = AArch64::LastTIBuiltin + 1;
+      End = AArch64::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::arm:
+    case llvm::Triple::armeb:
+    case llvm::Triple::thumb:
+    case llvm::Triple::thumbeb: {
+      Start = ARM::LastTIBuiltin + 1;
+      End = ARM::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::amdgcn:
+    case llvm::Triple::r600: {
+      Start = AMDGPU::LastTIBuiltin + 1;
+      End = AMDGPU::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::nvptx:
+    case llvm::Triple::nvptx64: {
+      Start = NVPTX::LastTIBuiltin + 1;
+      End = NVPTX::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::wasm32:
+    case llvm::Triple::wasm64: {
+      Start = WebAssembly::LastTIBuiltin + 1;
+      End = WebAssembly::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::riscv32:
+    case llvm::Triple::riscv64: {
+#if 0
+      Start = RISCV::LastTIBuiltin + 1;
+      End = RISCV::LastTSBuiltin;
+#endif
+      Start = 0;
+      End = 0;
+      break;
+    }
+    case llvm::Triple::xcore: {
+      Start = XCore::LastTIBuiltin + 1;
+      End = XCore::LastTSBuiltin;
+      break;
+    }
+    case llvm::Triple::msp430:
+    case llvm::Triple::sparc:
+    case llvm::Triple::sparcv9:
+    case llvm::Triple::sparcel:
+    case llvm::Triple::spir:
+    case llvm::Triple::spir64:
+      Start = 0;
+      End = 0;
+      break;
+    default:
+      llvm_unreachable("todo");
+    }
+
+    unsigned MissingCount = 0;
+    unsigned ExtraImmArg = 0;
+
+    for (unsigned BuiltinID = Start; BuiltinID != End; ++BuiltinID) {
+      unsigned ICEArguments = 0;
+      ASTContext::GetBuiltinTypeError Error;
+      Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
+
+
+      const char *Name = getASTContext().BuiltinInfo.getName(BuiltinID);
+      llvm::Intrinsic::ID IntrinsicID = llvm::Intrinsic::not_intrinsic;
+      StringRef Prefix =
+        llvm::Triple::getArchTypePrefix(Context.getTargetInfo().getTriple().getArch());
+      if (!Prefix.empty()) {
+        IntrinsicID = llvm::Intrinsic::getIntrinsicForGCCBuiltin(Prefix.data(), Name);
+        // NOTE we don't need to perform a compatibility flag check here since the
+        // intrinsics are declared in Builtins*.def via LANGBUILTIN which filter the
+        // MS builtins via ALL_MS_LANGUAGES and are filtered earlier.
+        if (IntrinsicID == llvm::Intrinsic::not_intrinsic)
+          IntrinsicID = llvm::Intrinsic::getIntrinsicForMSBuiltin(Prefix.data(), Name);
+      }
+
+
+      llvm::LLVMContext Ctx;
+      llvm::Module M("arst", Ctx);
+
+      llvm::Function *Decl = nullptr;
+
+
+      if (IntrinsicID != llvm::Intrinsic::not_intrinsic) {
+
+        if (!llvm::Intrinsic::isOverloaded(IntrinsicID)) {
+          Decl = llvm::Intrinsic::getDeclaration(
+            &M, (llvm::Intrinsic::ID)IntrinsicID, {});
+          if (!Decl) {
+            llvm_unreachable("no decl");
+            //report_fatal_error("no decl: " + Twine(Name));
+          }
+        } else {
+          llvm::dbgs() << "Skipping overloadable intrinsic: " << Twine(Name) << '\n';
+        }
+      }
+
+      // If any arguments are required to be ICE's, check and diagnose.
+      for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
+        // Skip arguments not required to be ICE's.
+        if ((ICEArguments & (1 << ArgNo)) == 0) {
+          if (Decl && Decl->hasParamAttribute(ArgNo, llvm::Attribute::ImmArg)) {
+            llvm::dbgs() << "EXTRA immarg: " << Twine(ArgNo) << " to " << Twine(Name) << '\n';
+            ++ExtraImmArg;
+          }
+          continue;
+        }
+
+
+        if (Decl && !Decl->hasParamAttribute(ArgNo, llvm::Attribute::ImmArg)) {
+          llvm::dbgs() << "Missing immarg: " + Twine(ArgNo) + " to " + Twine(Name) << '\n';
+          //report_fatal_error("Missing immarg: " + Twine(ArgNo) + " to " + Twine(Name));
+          ++MissingCount;
+          //llvm_unreachable("Missing immarg");
+        }
+
+        ICEArguments &= ~(1 << ArgNo);
+      }
+
+    }
+
+    assert(MissingCount == 0);
+    assert(ExtraImmArg == 0);
   }
 
   switch (BuiltinID) {