This patch looks fine to me. Please go ahead.
2011/6/25 Xiaohua Zhang <xiaohua_zh...@yahoo.com>:
> Hi,
>
> Could a gatekeeper help to review the fix for bug 799?
>
> Thanks,
> -Xiaohua
>
> The small test case is:
>
> #include <stdio.h>
> int rval = 0;
> typedef struct S { double i; } S;
> S f(void);
> typedef struct {
> int f1;
> struct S f2;
> } S1;
> S1 m;
> struct S t = { 0.0 };
> int main(void)
> {
> t.i = 12.345;
> m.f2 = f(); // return value should be in xmm0
> if (m.f2.i != t.i) {
> rval = -1;
> printf("Failed!\n");
> }
> return rval;
> }
> struct S f(void)
> {
> return t;
> }
>
> The WHIRL tree for "m.f2 = f()" looks like:
>
> MCALL 126 <1,53,f> # flags 0x7e {line: 1/20}
> MMLDID -1 <1,49,.preg_return_val> T<53,S,8>
> MSTID 8 <1,54,m> T<55,.anonymous.1,8> <field_id:2> {line: 0/0}
>
> After the RETURN_VAL & MLDID/MSTID lowering:
>
> MCALL 126 <1,53,f> # flags 0x7e {line: 1/20}
> I8I8LDID 1 <1,5,.preg_I8> T<5,.predef_I8,8> # $r1
> I8STID 8 <1,54,m> T<5,.predef_I8,8> {line: 0/0}
> F8F8LDID 17 <1,11,.preg_F8> T<11,.predef_F8,8> # $f0
> F8STID 16 <1,54,m> T<11,.predef_F8,8> {line: 0/0}
>
> The return value (S) is returned by two register: $r1 and $f0.
> By the ABI, the f()'s return value (type struct S) should be returned by one
> floating register $f0.
> The problem is in lower_return_mstid(), which takes MSTID's type (S1) as
> return type, didn't consider the field (f2) it accessed. So it used the
> wrong type (S1)to get return info, and the return value for S2 is by
> register $r1 and $f0.
>
> The fix is to get the accessed field type as return type.
>
>
>
>
>
> ----------------------
>
> Index: be/com/wn_lower.cxx
> ===================================================================
> --- be/com/wn_lower.cxx (revision 3659)
> +++ be/com/wn_lower.cxx (working copy)
> @@ -7239,7 +7239,12 @@
> ST *preg_st;
> WN *n_rhs;
> WN *wn = NULL; // init to prevent upward-exposed use
> - RETURN_INFO return_info = Get_Return_Info(WN_ty(tree),
> Complex_Not_Simulated
> + TY_IDX ty_idx = WN_ty(tree);
> +
> + if (WN_field_id (tree) != 0)
> + ty_idx = get_field_type (ty_idx, WN_field_id (tree));
> +
> + RETURN_INFO return_info = Get_Return_Info(ty_idx, Complex_Not_Simulated
> #ifdef TARG_X8664
> , last_call_ff2c_abi
> #endif
> @@ -7260,7 +7265,7 @@
> #endif
> WN *awn = WN_CreateLda(OPR_LDA, Pointer_Mtype, MTYPE_V,
> WN_store_offset(tree),
> - Make_Pointer_Type(WN_ty(tree)), WN_st_idx(tree));
> + Make_Pointer_Type(ty_idx), WN_st_idx(tree));
> awn = lower_expr(block, awn, actions);
> WN *n_call = add_fake_parm(call, awn, WN_ty(awn));
> WN_DELETE_FromBlock(block, call);
> @@ -7277,9 +7282,9 @@
> mtype = RETURN_INFO_mtype(return_info, i);
> desc = mtype;
> #ifdef KEY
> - if (MTYPE_byte_size(mtype) > TY_size(WN_ty(tree)) &&
> !MTYPE_float(mtype)){
> + if (MTYPE_byte_size(mtype) > TY_size(ty_idx) && !MTYPE_float(mtype)){
> desc = Mtype_AlignmentClass(1, MTYPE_type_class(mtype));
> - while (MTYPE_byte_size(desc) < TY_size(WN_ty(tree)))
> + while (MTYPE_byte_size(desc) < TY_size(ty_idx))
> desc = Mtype_next_alignment(desc);
> }
> #endif
> @@ -7287,7 +7292,7 @@
>
> #if defined(TARG_PPC32)
> if (preg_st == Int_Preg) {
> - UINT rem = TY_size(WN_ty(tree)) - i * 4;
> + UINT rem = TY_size(ty_idx) - i * 4;
> if (1 == rem) desc = MTYPE_I1;
> if (2 == rem) desc = MTYPE_I2;
> }
>
>
>
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>
>
--
Regards,
Lai Jian-Xin
------------------------------------------------------------------------------
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