Solve PR49479, File scope fp pragma should propagate to functions nested in struct, and initialization expressions

[mibintc]

Summary

Currently, the CurFPFeatures state is set to command line settings before semantic analysis of the nested member functions and initialization expressions, that's not correct. This patch fixes that.

[mibintc]

clang/lib/Parse/ParseDeclCXX.cpp

3419–3420

I remember worrying about this issue when I wrote the initial patch but I can't remember what my thinking was in putting this in. Nobody remarked about its presence or absence as far as I have found. Now that I read over the #pragma float_control in the C standard it seems clear that it should apply to these expressions. And why would the command line options take effect but not the pragma, doesn't make sense.

clang/test/CodeGen/fp-floatcontrol-stack.cpp

241

this is the test case from the bug report

[erichkeane]

The description of the problem, and hte patch and tests seem to make sense, so I think this should be ok. Please give some of the others a little bit of time before committing to speak their final bit, but LGTM .

[aaron.ballman]

LGTM as well, but feel free to give the other reviewers a chance to weigh in.

clang/lib/Parse/ParseDeclCXX.cpp

void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
   //   within function bodies, default arguments, exception-specifications, and
   //   brace-or-equal-initializers for non-static data members (including such
   //   things in nested classes).
   if (TagDecl && NonNestedClass) {
     // We are not inside a nested class. This class and its nested classes
     // are complete and we can parse the delayed portions of method
     // declarations and the lexed inline method definitions, along with any
     // delayed attributes.
 
-    // Save the state of Sema.FPFeatures, and change the setting
-    // to the levels specified on the command line.  Previous level
-    // will be restored when the RAII object is destroyed.
-    Sema::FPFeaturesStateRAII SaveFPFeaturesState(Actions);
-    FPOptionsOverride NewOverrides;
-    Actions.CurFPFeatures = NewOverrides.applyOverrides(getLangOpts());
-    Actions.FpPragmaStack.Act(Tok.getLocation(), Sema::PSK_Reset, StringRef(),
-                              {} /*unused*/);
-
     SourceLocation SavedPrevTokLocation = PrevTokLocation;
     ParseLexedPragmas(getCurrentClass());
     ParseLexedAttributes(getCurrentClass());
     ParseLexedMethodDeclarations(getCurrentClass());
 
     // We've finished with all pending member declarations.
     Actions.ActOnFinishCXXMemberDecls();
 
     ParseLexedMemberInitializers(getCurrentClass());

clang/test/CodeGen/fp-floatcontrol-stack.cpp

 #endif
 
 #ifndef FAST
 // Rule: precise must be enabled
 #pragma float_control(except, on)
 #endif
                                             float y();
 class ON {
-  // Settings for top level class initializer revert to command line
-  // source pragma's do not pertain.
+  // Settings for top level class initializer use program source setting.
   float z = 2 + y() * 7;
 //CHECK-LABEL: define {{.*}} void @_ZN2ONC2Ev{{.*}}
 #if DEFAULT
 //CHECK-DDEFAULT: call float {{.*}}llvm.fmuladd
 #endif
 #if EBSTRICT
 //Currently, same as default [command line options not considered]
 //CHECK-DEBSTRICT: call float {{.*}}llvm.fmuladd
 #endif
 #if NOHONOR
-//CHECK-NOHONOR: call nnan ninf float @llvm.fmuladd{{.*}}
+//CHECK-NOHONOR: call float {{.*}}llvm.fmuladd
 #endif
 #if FAST
-//CHECK-FAST: fmul fast float
-//CHECK-FAST: fadd fast float
+//CHECK-FAST: float {{.*}}llvm.fmuladd{{.*}}
 #endif
 };
 ON on;
 #pragma float_control(except, off)
 class OFF {
   float w = 2 + y() * 7;
 //CHECK-LABEL: define {{.*}} void @_ZN3OFFC2Ev{{.*}}
-#if DEFAULT
-//CHECK-DDEFAULT: call float {{.*}}llvm.fmuladd
-#endif
-#if EBSTRICT
-//CHECK-DEBSTRICT: call float {{.*}}llvm.fmuladd
-#endif
-#if NOHONOR
-//CHECK-NOHONOR: call nnan ninf float @llvm.fmuladd{{.*}}
-#endif
-#if FAST
-//CHECK-FAST: fmul fast float
-//CHECK-FAST: fadd fast float
-#endif
+//CHECK: call float {{.*}}llvm.fmuladd
 };
 OFF off;
+
+#pragma clang fp reassociate(on)
+struct MyComplex {
+  float xx;
+  float yy;
+  MyComplex(float x, float y) {
+    xx = x;
+    yy = y;
+  }
+  MyComplex() {}
+  const MyComplex operator+(const MyComplex other) const {
+//CHECK-LABEL: define {{.*}} @_ZNK9MyComplexplES_
+//CHECK: fadd reassoc float
+//CHECK: fadd reassoc float
+    return MyComplex(xx + other.xx, yy + other.yy);
+  }
+};
+MyComplex useAdd() {
+  MyComplex a (1, 3);
+  MyComplex b (2, 4);
+   return a + b;
+}