PNaCl: Disable parts of InstCombine that introduce *.with.overflow intrinsics

lib/Analysis/NaCl/PNaClABIVerifyModule.cpp

 //===- PNaClABIVerifyModule.cpp - Verify PNaCl ABI rules --------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // Verify module-level PNaCl ABI requirements (specifically those that do not
@@ skipping 181 matching lines @@
     case Intrinsic::eh_unwind_init:
     // We do not want to expose addresses to the user.
     case Intrinsic::frameaddress:
     case Intrinsic::returnaddress:
     // Not supporting stack protectors.
     case Intrinsic::stackprotector:
     // Var-args handling is done w/out intrinsics.
     case Intrinsic::vacopy:
     case Intrinsic::vaend:
     case Intrinsic::vastart:
+    // Disallow the *_with_overflow intrinsics because they return
+    // struct types.  All of them can be introduced by passing -ftrapv
+    // to Clang, which we do not support for now.  umul_with_overflow
+    // and uadd_with_overflow are introduced by Clang for C++'s new[],
+    // but ExpandArithWithOverflow expands out this use.
+    case Intrinsic::sadd_with_overflow:
+    case Intrinsic::ssub_with_overflow:
+    case Intrinsic::uadd_with_overflow:
+    case Intrinsic::usub_with_overflow:
+    case Intrinsic::smul_with_overflow:
+    case Intrinsic::umul_with_overflow:
       return false;
 
     // (3) Dev intrinsics.
     case Intrinsic::dbg_declare:
     case Intrinsic::dbg_value:
       return PNaClABIAllowDevIntrinsics || PNaClABIAllowDebugMetadata;
     case Intrinsic::cos: // Rounding not defined: support with fast-math?
     case Intrinsic::ctlz: // Support via compiler_rt if arch doesn't have it?
     case Intrinsic::ctpop: // Support via compiler_rt if arch doesn't have it?
     case Intrinsic::cttz: // Support via compiler_rt if arch doesn't have it?
     case Intrinsic::exp: // Rounding not defined: support with fast-math?
     case Intrinsic::exp2: // Rounding not defined: support with fast-math?
     case Intrinsic::expect: // From __builtin_expect.
     case Intrinsic::flt_rounds: // For FLT_ROUNDS macro from float.h.
       // We do not have fesetround() in newlib, can we return a
       // consistent rounding mode though?
     case Intrinsic::log: // Rounding not defined: support with fast-math?
     case Intrinsic::log2: // Rounding not defined: support with fast-math?
     case Intrinsic::log10: // Rounding not defined: support with fast-math?
     case Intrinsic::nacl_target_arch: // Used by translator self-build.
     case Intrinsic::pow: // Rounding is supposed to be the same as libm.
     case Intrinsic::powi: // Rounding not defined: support with fast-math?
     case Intrinsic::prefetch: // Could ignore if target doesn't support?
     case Intrinsic::sin: // Rounding not defined: support with fast-math?
     case Intrinsic::sqrt: // Rounding is defined, but setting errno up to libm.
     case Intrinsic::stackrestore: // Used to support C99 VLAs.
     case Intrinsic::stacksave: // Used to support C99 VLAs.
-    // the *_with_overflow return struct types, so we'll need to fix these.
-    case Intrinsic::sadd_with_overflow: // Introduced by -ftrapv
-    case Intrinsic::ssub_with_overflow:
-    case Intrinsic::uadd_with_overflow:
-    case Intrinsic::usub_with_overflow:
-    case Intrinsic::smul_with_overflow:
-    case Intrinsic::umul_with_overflow: // Introduced by c++ new[x * y].
       return PNaClABIAllowDevIntrinsics;
   }
 }
 
 bool PNaClABIVerifyModule::isWhitelistedMetadata(const NamedMDNode *MD) {
   return MD->getName().startswith("llvm.dbg.") && PNaClABIAllowDebugMetadata;
 }
 
 bool PNaClABIVerifyModule::runOnModule(Module &M) {
   if (!M.getModuleInlineAsm().empty()) {
@@ skipping 105 matching lines @@
 }
 
 char PNaClABIVerifyModule::ID = 0;
 INITIALIZE_PASS(PNaClABIVerifyModule, "verify-pnaclabi-module",
                 "Verify module for PNaCl", false, true)
 
 ModulePass *llvm::createPNaClABIVerifyModulePass(
     PNaClABIErrorReporter *Reporter) {
   return new PNaClABIVerifyModule(Reporter);
 }