r189440 - Disable loop vectorizer unrolling when no unrolling requested

[Hal Finkel]

Author: hfinkel
Date: Tue Aug 27 23:40:22 2013
New Revision: 189440

URL: http://llvm.org/viewvc/llvm-project?rev=189440&view=rev
Log:
Disable loop vectorizer unrolling when no unrolling requested

In addition to the regular loop unrolling transformation, the loop vectorizer
can also unroll loops. If no unrolling has specifically been requested (by
-fno-unroll-loops), and the loop vectorizer will be used, then add the backend
option to (also) prevent the loop vectorizer from unrolling loops.

I confirmed with Nadav (off list) that disabling vectorizer loop unrolling when
-fno-unroll-loops is provided is the desired behavior.

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=189440&r1=189439&r2=189440&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Tue Aug 27 23:40:22 2013
@@ -3382,9 +3382,19 @@ void Clang::ConstructJob(Compilation &C,
   OptSpecifier VectorizeAliasOption = EnableVec ? options::OPT_O_Group :
     options::OPT_fvectorize;
   if (Args.hasFlag(options::OPT_fvectorize, VectorizeAliasOption,
-                   options::OPT_fno_vectorize, EnableVec))
+                   options::OPT_fno_vectorize, EnableVec)) {
     CmdArgs.push_back("-vectorize-loops");
 
+    // In addition to the regular loop unrolling transformation, the loop
+    // vectorizer can also unroll loops. If no unrolling has specifically been
+    // requested, then also prevent the loop vectorizer from unrolling loops.
+    if (Args.hasFlag(options::OPT_fno_unroll_loops,
+        options::OPT_funroll_loops, false)) {
+      CmdArgs.push_back("-backend-option");
+      CmdArgs.push_back("-force-vector-unroll=1");
+    }
+  }
+
   // -fslp-vectorize is default.
   if (Args.hasFlag(options::OPT_fslp_vectorize,
                    options::OPT_fno_slp_vectorize, true))

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=189440&r1=189439&r2=189440&view=diff
==============================================================================
--- cfe/trunk/test/Driver/clang_f_opts.c (original)
+++ cfe/trunk/test/Driver/clang_f_opts.c Tue Aug 27 23:40:22 2013
@@ -45,6 +45,7 @@
 // CHECK-NO-UNROLL-LOOPS: "-fno-unroll-loops"
 
 // RUN: %clang -### -S -fvectorize %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
+// RUN: %clang -### -S -fvectorize -fno-unroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE-NO-UNROLL %s
 // RUN: %clang -### -S -fno-vectorize -fvectorize %s 2>&1 | FileCheck -check-prefix=CHECK-VECTORIZE %s
 // RUN: %clang -### -S -fno-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
 // RUN: %clang -### -S -fvectorize -fno-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
@@ -65,6 +66,8 @@
 // RUN: %clang -### -S -Oz %s 2>&1 | FileCheck -check-prefix=CHECK-NO-VECTORIZE %s
 // CHECK-VECTORIZE: "-vectorize-loops"
 // CHECK-NO-VECTORIZE-NOT: "-vectorize-loops"
+// CHECK-VECTORIZE-NOT: "-backend-option" "-force-vector-unroll=1"
+// CHECK-VECTORIZE-NO-UNROLL: "-backend-option" "-force-vector-unroll=1"
 
 // RUN: %clang -### -S -fslp-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-SLP-VECTORIZE %s
 // RUN: %clang -### -S -fno-slp-vectorize -fslp-vectorize %s 2>&1 | FileCheck -check-prefix=CHECK-SLP-VECTORIZE %s