Driver: parse -mcmodel earlier

This addresses an existing FIXME item in the driver.  The code model flag was
parsed in the actual tool rather than in the driver.  This was problematic since
the value may be invalid.  In that case, we would silently treat it as a default
value in non-assert builds, and abort in assert builds.  Add a check in the
driver to validate that the value being passed is valid, and if not provide a
proper error message.

llvm-svn: 208275

1 files changed, 11 insertions, 14 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 8d4f69afc35..85d8b645731 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -14,6 +14,7 @@
 #include "clang/Frontend/CodeGenOptions.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/Utils.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/Bitcode/BitcodeWriterPass.h"
 #include "llvm/CodeGen/RegAllocRegistry.h"
 #include "llvm/CodeGen/SchedulerRegistry.h"
@@ -378,20 +379,16 @@ TargetMachine *EmitAssemblyHelper::CreateTargetMachine(bool MustCreateTM) {
   TargetMachine::setFunctionSections(CodeGenOpts.FunctionSections);
   TargetMachine::setDataSections    (CodeGenOpts.DataSections);
 
-  // FIXME: Parse this earlier.
-  llvm::CodeModel::Model CM;
-  if (CodeGenOpts.CodeModel == "small") {
-    CM = llvm::CodeModel::Small;
-  } else if (CodeGenOpts.CodeModel == "kernel") {
-    CM = llvm::CodeModel::Kernel;
-  } else if (CodeGenOpts.CodeModel == "medium") {
-    CM = llvm::CodeModel::Medium;
-  } else if (CodeGenOpts.CodeModel == "large") {
-    CM = llvm::CodeModel::Large;
-  } else {
-    assert(CodeGenOpts.CodeModel.empty() && "Invalid code model!");
-    CM = llvm::CodeModel::Default;
-  }
+  unsigned CodeModel =
+    llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
+      .Case("small", llvm::CodeModel::Small)
+      .Case("kernel", llvm::CodeModel::Kernel)
+      .Case("medium", llvm::CodeModel::Medium)
+      .Case("large", llvm::CodeModel::Medium)
+      .Case("default", llvm::CodeModel::Default)
+      .Default(~0u);
+  assert(CodeModel != ~0u && "invalid code model!");
+  llvm::CodeModel::Model CM = static_cast<llvm::CodeModel::Model>(CodeModel);
 
   SmallVector<const char *, 16> BackendArgs;
   BackendArgs.push_back("clang"); // Fake program name.