If triple is armv7 / thumbv7 and a CPU is specified, do not automatically assume

the feature set of v7a. This comes about if the user specifies something like
-arch armv7 -mcpu=cortex-m3. We shouldn't be generating instructions such as
uxtab in this case.

rdar://11318438


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155601 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 16 insertions, 7 deletions

diff --git a/lib/Target/ARM/ARMSubtarget.cpp b/lib/Target/ARM/ARMSubtarget.cpp
index 5be0d2b819..25e611bee4 100644
--- a/lib/Target/ARM/ARMSubtarget.cpp
+++ b/lib/Target/ARM/ARMSubtarget.cpp
@@ -83,7 +83,7 @@ ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
   // Insert the architecture feature derived from the target triple into the
   // feature string. This is important for setting features that are implied
   // based on the architecture version.
-  std::string ArchFS = ARM_MC::ParseARMTriple(TT);
+  std::string ArchFS = ARM_MC::ParseARMTriple(TT, CPUString);
   if (!FS.empty()) {
     if (!ArchFS.empty())
       ArchFS = ArchFS + "," + FS;
diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
index e3512cda3a..67f6f6f352 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
@@ -35,7 +35,7 @@
 
 using namespace llvm;
 
-std::string ARM_MC::ParseARMTriple(StringRef TT) {
+std::string ARM_MC::ParseARMTriple(StringRef TT, StringRef CPU) {
   // Set the boolean corresponding to the current target triple, or the default
   // if one cannot be determined, to true.
   unsigned Len = TT.size();
@@ -62,9 +62,18 @@ std::string ARM_MC::ParseARMTriple(StringRef TT) {
         // v7em: FeatureNoARM, FeatureDB, FeatureHWDiv, FeatureDSPThumb2,
         //       FeatureT2XtPk, FeatureMClass
         ARMArchFeature = "+v7,+noarm,+db,+hwdiv,+t2dsp,t2xtpk,+mclass";
-      } else
-        // v7a: FeatureNEON, FeatureDB, FeatureDSPThumb2, FeatureT2XtPk
-        ARMArchFeature = "+v7,+neon,+db,+t2dsp,+t2xtpk";
+      } else {
+        // v7 CPUs have lots of different feature sets. If no CPU is specified,
+        // then assume v7a (e.g. cortex-a8) feature set. Otherwise, return
+        // the "minimum" feature set and use CPU string to figure out the exact
+        // features.
+        if (CPU == "generic")
+          // v7a: FeatureNEON, FeatureDB, FeatureDSPThumb2, FeatureT2XtPk
+          ARMArchFeature = "+v7,+neon,+db,+t2dsp,+t2xtpk";
+        else
+          // Use CPU to figure out the exact features.
+          ARMArchFeature = "+v7";
+      }
     } else if (SubVer == '6') {
       if (Len >= Idx+3 && TT[Idx+1] == 't' && TT[Idx+2] == '2')
         ARMArchFeature = "+v6t2";
@@ -94,7 +103,7 @@ std::string ARM_MC::ParseARMTriple(StringRef TT) {
 
 MCSubtargetInfo *ARM_MC::createARMMCSubtargetInfo(StringRef TT, StringRef CPU,
                                                   StringRef FS) {
-  std::string ArchFS = ARM_MC::ParseARMTriple(TT);
+  std::string ArchFS = ARM_MC::ParseARMTriple(TT, CPU);
   if (!FS.empty()) {
     if (!ArchFS.empty())
       ArchFS = ArchFS + "," + FS.str();
diff --git a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
index 88472d7ffc..57719369c6 100644
--- a/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
+++ b/lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h
@@ -31,7 +31,7 @@ class raw_ostream;
 extern Target TheARMTarget, TheThumbTarget;
 
 namespace ARM_MC {
-  std::string ParseARMTriple(StringRef TT);
+  std::string ParseARMTriple(StringRef TT, StringRef CPU);
 
   /// createARMMCSubtargetInfo - Create a ARM MCSubtargetInfo instance.
   /// This is exposed so Asm parser, etc. do not need to go through