From 99662a156055de9f46b3cababbf7032e68ed961b Mon Sep 17 00:00:00 2001
From: Arnold Schwaighofer <aschwaighofer@apple.com>
Date: Tue, 13 Aug 2013 15:46:23 +0000
Subject: [PATCH] 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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@188280 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Driver/Tools.cpp       | 43 ++++++++++++++++++++++++++++++++------
 test/Driver/clang_f_opts.c | 12 +++++++++++
 2 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 13d36b0312..a6be76ea3a 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1858,6 +1858,37 @@ static bool isOptimizationLevelFast(const ArgList &Args) {
   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, const JobAction &JA,
                    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.
diff --git a/test/Driver/clang_f_opts.c b/test/Driver/clang_f_opts.c
index 87843d3b22..e1005d713a 100644
--- a/test/Driver/clang_f_opts.c
+++ b/test/Driver/clang_f_opts.c
@@ -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"
 
-- 
2.40.0