Fix the check for regparm in FunctionType::ExtInfo

[chill]

Summary

getHasRegParm() was working under the assumption that the RegParm bits are the
last field, which is no longer true, after adding the NoCfCheck and CmseNSCall
fields.

This causes a spurious "regparm 0" attribute to appear when a function type is
declared with either __attribute__((nocf_check)) or
__attribute__((cmse_nonsecure_call)).

[snidertm]

Looks good to me. Sorry about my confusion over this code in the CMSE attributes review. ~ Todd

clang/include/clang/AST/Type.h

3522

I misread the big ~(flag1 | flag2 | etc) calculation of the mask before. This makes it obvious.

[chill]

Added a REQUIRES line to the test.

clang/include/clang/AST/Type.h

class ExtInfo {
     // |  CC  |noreturn|produces|nocallersavedregs|regparm|nocfcheck|cmsenscall|
     // |0 .. 4|   5    |    6   |       7         |8 .. 10|    11   |    12    |
     //
     // regparm is either 0 (no regparm attribute) or the regparm value+1.
     enum { CallConvMask = 0x1F };
     enum { NoReturnMask = 0x20 };
     enum { ProducesResultMask = 0x40 };
     enum { NoCallerSavedRegsMask = 0x80 };
-    enum { NoCfCheckMask = 0x800 };
-    enum { CmseNSCallMask = 0x1000 };
     enum {
-      RegParmMask = ~(CallConvMask | NoReturnMask | ProducesResultMask |
-                      NoCallerSavedRegsMask | NoCfCheckMask | CmseNSCallMask),
+      RegParmMask =  0x700,
       RegParmOffset = 8
-    }; // Assumed to be the last field
+    };
+    enum { NoCfCheckMask = 0x800 };
+    enum { CmseNSCallMask = 0x1000 };
     uint16_t Bits = CC_C;
 
     ExtInfo(unsigned Bits) : Bits(static_cast<uint16_t>(Bits)) {}
 
   public:
     // Constructor with no defaults. Use this when you know that you
     // have all the elements (when reading an AST file for example).
     ExtInfo(bool noReturn, bool hasRegParm, unsigned regParm, CallingConv cc,
public:
     // of the canonical type.
     ExtInfo(CallingConv CC) : Bits(CC) {}
 
     bool getNoReturn() const { return Bits & NoReturnMask; }
     bool getProducesResult() const { return Bits & ProducesResultMask; }
     bool getCmseNSCall() const { return Bits & CmseNSCallMask; }
     bool getNoCallerSavedRegs() const { return Bits & NoCallerSavedRegsMask; }
     bool getNoCfCheck() const { return Bits & NoCfCheckMask; }
-    bool getHasRegParm() const { return (Bits >> RegParmOffset) != 0; }
+    bool getHasRegParm() const { return ((Bits & RegParmMask) >> RegParmOffset) != 0; }
 
     unsigned getRegParm() const {
       unsigned RegParm = (Bits & RegParmMask) >> RegParmOffset;
       if (RegParm > 0)
         --RegParm;
       return RegParm;
     }
 

clang/test/AST/spurious-regparm.c

+// RUN: %clang_cc1 -triple armv8.1m.main-eabi -mcmse -fsyntax-only %s -ast-dump | FileCheck %s
+// REQUIRES: arm-registered-target
+typedef int (*fn_t)(int) __attribute__((cmse_nonsecure_call));
+// CHECK-NOT: regparm 0