568393 - msvc 2008 compiler generates bad code for CallInfo static initializer

Status: RESOLVED FIXED

(Tamarin Graveyard :: Baseline JIT (CodegenLIR), defect)

Description

[Rick Reitmaier]

CallInfo contains a mix of uint32_t and uint8_t bitfields that appears to confuses MSVC (see below).

Changing the fields to uniformly use uin32_t fixes the issue:

    struct CallInfo
    {
        uintptr_t   _address;
        uint32_t    _typesig:27;     // 9 3-bit fields indicating arg type, by ARGTYPE above (including ret type): a1 a2 a3 a4\
 a5 ret                                                                                                                        
        AbiKind     _abi:3;
	uint8_t     _isPure:1;      // _isPure=1 means no side-effects, result only depends on args                            
        AccSet      _storeAccSet;   // access regions stored by the function                                                   
	verbose_only ( const char* _name; )




The following program produces an incorrect result when using msvc 2008:

// cl /Fa bug.cpp
//
// Look at assembly output and observe that the lower word of 
// S.a is being shoved into S.c  :
//
//    ...
//    and eax, 0x7ffffff     
//    mov 0(_temp), eax
//    mov 0(s), eax
//    mov cl, 0(_temp)   <= baaaad
//    mov 4(s), cl
//
#include "stdio.h"

// notice last field of structure below is a unsigned char
typedef struct _S
{ 
	unsigned a:27;
	unsigned b:3;
	unsigned char c:1;  // @FIX: change 'unsigned char' to 'unsigned'
} S;

// this function exists only to force 's' to be a dynamic initializer
int rubish(int a) { return 1; }

S s = { rubish(0),0,0 };

void main(char* argv, int argc) {
   printf("s.c is %d - should be 0\n", s.c);
}

Comment 1

[Rick Reitmaier]

Attachment: hmm

previously review by wmaddox - pushed http://hg.mozilla.org/projects/nanojit-central/rev/f7c07b8ca96f

Comment 2

[Rick Reitmaier]

TR - http://hg.mozilla.org/tamarin-redux/rev/e3cf485a27fa

Comment 3

[Nicholas Nethercote [inactive]]

http://hg.mozilla.org/tracemonkey/rev/f0d5f28aa61e

Comment 4

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/3b300e72d88b