[cfe-dev] Address space extensions (adding type modifier keywords)

[Daniel Marjamäki via cfe-dev]

Hello!

I am not an expert. But I think you should use address space attributes. This code compiles without errors:

#define xstglocal  __attribute__((address_space(0)))
#define xstgblock  __attribute__((address_space(256)))
#define xstgglobal  __attribute__((address_space(257)))

int* xstglocal  lp_i;       // Local pointer to any integer
int* xstgblock  b_pi;       // Block pointer to any integer
int* xstgglobal g_pi;       // Global pointer to any integer

xstgglobal int* xstglocal  vp_li;   // Local pointer to global integer
xstglocal  int* xstgblock  vp_bi;   // Block pointer to local integer
xstgblock  int* xstgglobal vp_gi;   // Global pointer to block integer

Best regards,
Daniel Marjamäki

..................................................................................................................
Daniel Marjamäki Senior Engineer
Evidente ES East AB  Warfvinges väg 34  SE-112 51 Stockholm  Sweden

Mobile:                 +46 (0)709 12 42 62
E-mail:                 Daniel.Marjamaki<mailto:Daniel.Marjamaki at evidente.se>@evidente.se<mailto:Daniel.Marjamaki at evidente.se>

www.evidente.se
________________________________
From: cfe-dev [cfe-dev-bounces at lists.llvm.org] on behalf of Phil Tomson via cfe-dev [cfe-dev at lists.llvm.org]
Sent: 14 October 2016 03:35
To: cfe-dev at lists.llvm.org
Subject: [cfe-dev] Address space extensions (adding type modifier keywords)

Our architecture has a somewhat different memory model with three different address spaces: local, block, global.

Some time ago (prior to my involvement in our project) our address space extensions were added to the frontend so that we can write:

volatile   int v_i;
xstglocal  int l_i;
xstgblock  int b_i;
xstgglobal int g_i;

volatile   int* p_vi;       // Regular pointer to volatile integer
xstglocal  int* p_li;       // Regular pointer to local integer
xstgblock  int* b_pi;       // Regular pointer to block integer
xstgglobal int* g_pi;       // Regular pointer to global integer

int* volatile   vp_i;       // Volatile pointer to regular integer

These address space modifiers (xstglocal, xstgblock, xstgglobal) are used to determine which address space data is stored in. The above will compile just fine.

However, originally this work was done for clang/llvm 3.2. After we moved to 3.6 we found that the following (which used to work in 3.2) no longer works in 3.6:

int* xstglocal  lp_i;       // Local pointer to any integer
int* xstgblock  b_pi;       // Block pointer to any integer
int* xstgglobal g_pi;       // Global pointer to any integer

xstgglobal int* xstglocal  vp_li;   // Local pointer to global integer
xstglocal  int* xstgblock  vp_bi;   // Block pointer to local integer
xstgblock  int* xstgglobal vp_gi;   // Global pointer to block integer

These result in front end errors:

issue.c:13:7: error: expected identifier or '('
int * xstglocal  lp_i;       // Local pointer to any integer
      ^
issue.c:14:7: error: expected identifier or '('
int * xstgblock  b_pi;       // Block pointer to any integer
      ^
issue.c:15:7: error: expected identifier or '('
int * xstgglobal g_pi;       // Global pointer to any integer
      ^
issue.c:20:18: error: expected identifier or '('
xstgglobal int * xstglocal  vp_li;   // Local pointer to global integer
                 ^
issue.c:21:18: error: expected identifier or '('
xstglocal  int * xstgblock  vp_bi;   // Block pointer to local integer
                 ^
issue.c:22:18: error: expected identifier or '('
xstgblock  int * xstgglobal vp_gi;   // Global pointer to block integer
                 ^
6 errors generated.

It looks as though these address space extension keywords were added in
TokenKinds.def:
// XSTG address space qualifiers
KEYWORD(xstgglobal                  , KEYXSTG)
KEYWORD(xstgblock                   , KEYXSTG)
KEYWORD(xstglocal                   , KEYXSTG)

As well as in Attr.td:

def XSTGLocalAddressSpace : TypeAttr {
  let Spellings = [Keyword<"xstglocal">];
  let Documentation = [Undocumented];
}

def XSTGBlockAddressSpace : TypeAttr {
  let Spellings = [Keyword<"xstgblock">];
  let Documentation = [Undocumented];
}

def XSTGGlobalAddressSpace : TypeAttr {
  let Spellings = [Keyword<"xstgglobal">];
  let Documentation = [Undocumented];
}

with some support in ParseDecl.cpp.

Was there an API change between clang 3.2 and 3.6 that might have broken this? Any pointers on how I might fix these errors?

Thanks.

Phil



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