r213935 - Revert part of r206963

[Nico Weber]

Should this be merged to 3.5? 3.4 had this warning too, right?


On Fri, Jul 25, 2014 at 3:19 AM, James Molloy <james.molloy at arm.com> wrote:

> Author: jamesm
> Date: Fri Jul 25 05:19:47 2014
> New Revision: 213935
>
> URL: http://llvm.org/viewvc/llvm-project?rev=213935&view=rev
> Log:
> Revert part of r206963
>
> Specifically the part where we removed a warning to be compatible with
> GCC, which has been widely regarded as a bad idea.
>
> I'm not quite happy with how obtuse this warning is, especially in the
> fairly common case of a 32-bit integer literal, so I've got another patch
> awaiting review that adds a fixit to reduce confusion.
>
>
> Modified:
>     cfe/trunk/lib/Basic/Targets.cpp
>     cfe/trunk/test/Sema/arm64-inline-asm.c
>     cfe/trunk/test/Sema/inline-asm-validate.c
>
> Modified: cfe/trunk/lib/Basic/Targets.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Targets.cpp?rev=213935&r1=213934&r2=213935&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Basic/Targets.cpp (original)
> +++ cfe/trunk/lib/Basic/Targets.cpp Fri Jul 25 05:19:47 2014
> @@ -4503,6 +4503,33 @@ public:
>      return false;
>    }
>
> +  virtual bool validateConstraintModifier(StringRef Constraint,
> +                                          const char Modifier,
> +                                          unsigned Size) const {
> +    // Strip off constraint modifiers.
> +    while (Constraint[0] == '=' || Constraint[0] == '+' || Constraint[0]
> == '&')
> +      Constraint = Constraint.substr(1);
> +
> +    switch (Constraint[0]) {
> +    default:
> +      return true;
> +    case 'z':
> +    case 'r': {
> +      switch (Modifier) {
> +      case 'x':
> +      case 'w':
> +        // For now assume that the person knows what they're
> +        // doing with the modifier.
> +        return true;
> +      default:
> +        // By default an 'r' constraint will be in the 'x'
> +        // registers.
> +        return Size == 64;
> +      }
> +    }
> +    }
> +  }
> +
>    virtual const char *getClobbers() const { return ""; }
>
>    int getEHDataRegisterNumber(unsigned RegNo) const {
>
> Modified: cfe/trunk/test/Sema/arm64-inline-asm.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/arm64-inline-asm.c?rev=213935&r1=213934&r2=213935&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Sema/arm64-inline-asm.c (original)
> +++ cfe/trunk/test/Sema/arm64-inline-asm.c Fri Jul 25 05:19:47 2014
> @@ -1,9 +1,9 @@
>  // RUN: %clang_cc1 -triple arm64-apple-ios7.1 -fsyntax-only -verify %s
> -// expected-no-diagnostics
>
>  void foo() {
>    asm volatile("USE(%0)" :: "z"(0LL));
>    asm volatile("USE(%x0)" :: "z"(0LL));
>    asm volatile("USE(%w0)" :: "z"(0));
>
> +  asm volatile("USE(%0)" :: "z"(0)); // expected-warning {{value size
> does not match register size specified by the constraint and modifier}}
>  }
>
> Modified: cfe/trunk/test/Sema/inline-asm-validate.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/inline-asm-validate.c?rev=213935&r1=213934&r2=213935&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Sema/inline-asm-validate.c (original)
> +++ cfe/trunk/test/Sema/inline-asm-validate.c Fri Jul 25 05:19:47 2014
> @@ -1,9 +1,8 @@
>  // RUN: %clang_cc1 -triple arm64-apple-macosx10.8.0 -fsyntax-only -verify
> %s
> -// expected-no-diagnostics
>
>  unsigned t, r, *p;
>
>  int foo (void) {
> -  __asm__ __volatile__( "stxr   %w[_t], %[_r], [%[_p]]" : [_t] "=&r" (t)
> : [_p] "p" (p), [_r] "r" (r) : "memory");
> +  __asm__ __volatile__( "stxr   %w[_t], %[_r], [%[_p]]" : [_t] "=&r" (t)
> : [_p] "p" (p), [_r] "r" (r) : "memory"); // expected-warning{{value size
> does not match register size specified by the constraint and modifier}}
>    return 1;
>  }
>
>
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