r188280 - Move logic to enable the vectorizer to clang

[Arnold Schwaighofer]

Author: arnolds
Date: Tue Aug 13 10:46:23 2013
New Revision: 188280

URL: http://llvm.org/viewvc/llvm-project?rev=188280&view=rev
Log:
Move logic to enable the vectorizer to clang

We used to decide whether to really vectorize depending on the optimization
level in PassManagerBuilder.

This patch moves this decision to the clang driver. We look at the optimization
level and whether the f(no-)vectorize is set and decide whether to vectorize.

This allows us to simplify the logic in PassManagerBuilder to just a check for
whether the vectorizer should run or not.

We now do the right thing for:
$ clang -O1 -fvectorize
$ clang -fno-vectorize -O3

Modified:
    cfe/trunk/lib/Driver/Tools.cpp
    cfe/trunk/test/Driver/clang_f_opts.c

Modified: cfe/trunk/lib/Driver/Tools.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=188280&r1=188279&r2=188280&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Tue Aug 13 10:46:23 2013
@@ -1858,6 +1858,37 @@ static bool isOptimizationLevelFast(cons
   return false;
 }
 
+/// \brief Vectorize at all optimization levels greater than 1 except for -Oz.
+static bool shouldEnableVectorizerAtOLevel(const ArgList &Args) {
+  if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
+    if (A->getOption().matches(options::OPT_O4) ||
+        A->getOption().matches(options::OPT_Ofast))
+      return true;
+
+    if (A->getOption().matches(options::OPT_O0))
+      return false;
+
+    assert(A->getOption().matches(options::OPT_O) && "Must have a -O flag");
+
+    // Vectorize -O (which really is -O2), -Os.
+    StringRef S(A->getValue());
+    if (S == "s" || S.empty())
+      return true;
+
+    // Don't vectorize -Oz.
+    if (S == "z")
+      return false;
+
+    unsigned OptLevel = 0;
+    if (S.getAsInteger(10, OptLevel))
+      return false;
+
+    return OptLevel > 1;
+  }
+
+  return false;
+}
+
 void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                          const InputInfo &Output,
                          const InputInfoList &Inputs,
@@ -3336,14 +3367,14 @@ void Clang::ConstructJob(Compilation &C,
                    false))
     CmdArgs.push_back("-fasm-blocks");
 
-  // If -Ofast is the optimization level, then -fvectorize should be enabled.
-  // This alias option is being used to simplify the hasFlag logic.
-  OptSpecifier VectorizeAliasOption = OFastEnabled ? options::OPT_Ofast :
+  // Enable vectorization per default according to the optimization level
+  // selected. For optimization levels that want vectorization we use the alias
+  // option to simplify the hasFlag logic.
+  bool EnableVec = shouldEnableVectorizerAtOLevel(Args);
+  OptSpecifier VectorizeAliasOption = EnableVec ? options::OPT_O_Group :
     options::OPT_fvectorize;
-
-  // -fvectorize is default.
   if (Args.hasFlag(options::OPT_fvectorize, VectorizeAliasOption,
-                   options::OPT_fno_vectorize, true))
+                   options::OPT_fno_vectorize, EnableVec))
     CmdArgs.push_back("-vectorize-loops");
 
   // -fslp-vectorize is default.

Modified: cfe/trunk/test/Driver/clang_f_opts.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/clang_f_opts.c?rev=188280&r1=188279&r2=188280&view=diff
==============================================================================
--- cfe/trunk/test/Driver/clang_f_opts.c (original)
+++ cfe/trunk/test/Driver/clang_f_opts.c Tue Aug 13 10:46:23 2013
@@ -52,6 +52,18 @@
 // RUN: %clang -### -S -fno-tree-vectorize -fvectorize %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
 // RUN: %clang -### -S -fno-tree-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
 // RUN: %clang -### -S -ftree-vectorize -fno-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
+// RUN: %clang -### -S -O %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -O2 %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -O3 %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -O4 %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -fno-vectorize -O3 %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -O1 -fvectorize %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -Ofast %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
+// RUN: %clang -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
+// RUN: %clang -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
+// RUN: %clang -### -S -Oz %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
 // CHECK-VECTORIZE: "-vectorize-loops"
 // CHECK-NO-VECTORIZE-NOT: "-vectorize-loops"