Merging r325446:

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r325446 | dim | 2018-02-17 13:04:35 -0800 (Sat, 17 Feb 2018) | 28 lines

[X86] Add 'sahf' CPU feature to frontend

Summary:
Make clang accept `-msahf` (and `-mno-sahf`) flags to activate the
`+sahf` feature for the backend, for bug 36028 (Incorrect use of
pushf/popf enables/disables interrupts on amd64 kernels).  This was
originally submitted in bug 36037 by Jonathan Looney
<jonlooney@gmail.com>.

As described there, GCC also uses `-msahf` for this feature, and the
backend already recognizes the `+sahf` feature. All that is needed is to
teach clang to pass this on to the backend.

The mapping of feature support onto CPUs may not be complete; rather, it
was chosen to match LLVM's idea of which CPUs support this feature (see
lib/Target/X86/X86.td).

I also updated the affected test case (CodeGen/attr-target-x86.c) to
match the emitted output.

Reviewers: craig.topper, coby, efriedma, rsmith

Reviewed By: craig.topper

Subscribers: emaste, cfe-commits

Differential Revision: https://reviews.llvm.org/D43394

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llvm-svn: 332560

clang/include/clang/Driver/Options.td

@@ -2562,6 +2562,8 @@ def mrtm : Flag<["-"], "mrtm">, Group<m_x86_Features_Group>;
 def mno_rtm : Flag<["-"], "mno-rtm">, Group<m_x86_Features_Group>;
 def mrdseed : Flag<["-"], "mrdseed">, Group<m_x86_Features_Group>;
 def mno_rdseed : Flag<["-"], "mno-rdseed">, Group<m_x86_Features_Group>;
+def msahf : Flag<["-"], "msahf">, Group<m_x86_Features_Group>;
+def mno_sahf : Flag<["-"], "mno-sahf">, Group<m_x86_Features_Group>;
 def msgx : Flag<["-"], "msgx">, Group<m_x86_Features_Group>;
 def mno_sgx : Flag<["-"], "mno-sgx">, Group<m_x86_Features_Group>;
 def msha : Flag<["-"], "msha">, Group<m_x86_Features_Group>;

clang/lib/Basic/Targets/X86.cpp

@@ -198,6 +198,7 @@ bool X86TargetInfo::initFeatureMap(
     LLVM_FALLTHROUGH;
   case CK_Core2:
     setFeatureEnabledImpl(Features, "ssse3", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     LLVM_FALLTHROUGH;
   case CK_Yonah:
   case CK_Prescott:
@@ -239,6 +240,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "ssse3", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
     setFeatureEnabledImpl(Features, "cx16", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     break;
 
   case CK_KNM:
@@ -269,6 +271,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "xsaveopt", true);
     setFeatureEnabledImpl(Features, "xsave", true);
     setFeatureEnabledImpl(Features, "movbe", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     break;
 
   case CK_K6_2:
@@ -282,6 +285,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "sse4a", true);
     setFeatureEnabledImpl(Features, "lzcnt", true);
     setFeatureEnabledImpl(Features, "popcnt", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     LLVM_FALLTHROUGH;
   case CK_K8SSE3:
     setFeatureEnabledImpl(Features, "sse3", true);
@@ -315,6 +319,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "prfchw", true);
     setFeatureEnabledImpl(Features, "cx16", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     break;
 
   case CK_ZNVER1:
@@ -338,6 +343,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "prfchw", true);
     setFeatureEnabledImpl(Features, "rdrnd", true);
     setFeatureEnabledImpl(Features, "rdseed", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     setFeatureEnabledImpl(Features, "sha", true);
     setFeatureEnabledImpl(Features, "sse4a", true);
     setFeatureEnabledImpl(Features, "xsave", true);
@@ -372,6 +378,7 @@ bool X86TargetInfo::initFeatureMap(
     setFeatureEnabledImpl(Features, "cx16", true);
     setFeatureEnabledImpl(Features, "fxsr", true);
     setFeatureEnabledImpl(Features, "xsave", true);
+    setFeatureEnabledImpl(Features, "sahf", true);
     break;
   }
   if (!TargetInfo::initFeatureMap(Features, Diags, CPU, FeaturesVec))
@@ -768,6 +775,8 @@ bool X86TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasRetpoline = true;
     } else if (Feature == "+retpoline-external-thunk") {
       HasRetpolineExternalThunk = true;
+    } else if (Feature == "+sahf") {
+      HasLAHFSAHF = true;
     }
 
     X86SSEEnum Level = llvm::StringSwitch<X86SSEEnum>(Feature)
@@ -1240,6 +1249,7 @@ bool X86TargetInfo::isValidFeatureName(StringRef Name) const {
       .Case("rdrnd", true)
       .Case("rdseed", true)
       .Case("rtm", true)
+      .Case("sahf", true)
       .Case("sgx", true)
       .Case("sha", true)
       .Case("shstk", true)
@@ -1313,6 +1323,7 @@ bool X86TargetInfo::hasFeature(StringRef Feature) const {
       .Case("retpoline", HasRetpoline)
       .Case("retpoline-external-thunk", HasRetpolineExternalThunk)
       .Case("rtm", HasRTM)
+      .Case("sahf", HasLAHFSAHF)
       .Case("sgx", HasSGX)
       .Case("sha", HasSHA)
       .Case("shstk", HasSHSTK)

clang/lib/Basic/Targets/X86.h

@@ -98,6 +98,7 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
   bool HasPREFETCHWT1 = false;
   bool HasRetpoline = false;
   bool HasRetpolineExternalThunk = false;
+  bool HasLAHFSAHF = false;
 
   /// \brief Enumeration of all of the X86 CPUs supported by Clang.
   ///

clang/test/CodeGen/attr-target-x86.c

@@ -37,10 +37,10 @@ int __attribute__((target("arch=lakemont,mmx"))) lake(int a) { return 4; }
 // CHECK: qq{{.*}} #6
 // CHECK: lake{{.*}} #7
 // CHECK: #0 = {{.*}}"target-cpu"="i686" "target-features"="+x87"
-// CHECK: #1 = {{.*}}"target-cpu"="ivybridge" "target-features"="+aes,+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
+// CHECK: #1 = {{.*}}"target-cpu"="ivybridge" "target-features"="+aes,+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt"
 // CHECK: #2 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-aes,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-gfni,-pclmul,-sha,-sse2,-sse3,-sse4.1,-sse4.2,-sse4a,-ssse3,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
 // CHECK: #3 = {{.*}}"target-cpu"="i686" "target-features"="+mmx,+popcnt,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87"
 // CHECK: #4 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-avx,-avx2,-avx512bitalg,-avx512bw,-avx512cd,-avx512dq,-avx512er,-avx512f,-avx512ifma,-avx512pf,-avx512vbmi,-avx512vbmi2,-avx512vl,-avx512vnni,-avx512vpopcntdq,-f16c,-fma,-fma4,-sse4.1,-sse4.2,-vaes,-vpclmulqdq,-xop,-xsave,-xsaveopt"
-// CHECK: #5 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt,-aes,-vaes"
+// CHECK: #5 = {{.*}}"target-cpu"="ivybridge" "target-features"="+avx,+cx16,+f16c,+fsgsbase,+fxsr,+mmx,+pclmul,+popcnt,+rdrnd,+sahf,+sse,+sse2,+sse3,+sse4.1,+sse4.2,+ssse3,+x87,+xsave,+xsaveopt,-aes,-vaes"
 // CHECK: #6 = {{.*}}"target-cpu"="i686" "target-features"="+x87,-3dnow,-3dnowa,-mmx"
 // CHECK: #7 = {{.*}}"target-cpu"="lakemont" "target-features"="+mmx"