Re: DCE fix

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Jul 23, 2009 at 10:23 AM, Jan Hubicka<hubicka@ucw.cz> wrote:
> Hi,
> the problem exposed in testcase is caused by PHI in dead BB defining
> virtual operand used by dead stmt. ?This dead stmt define vop used by
> live stmt.
>
> We handle the first case by replacing uses by SSA_NAME's var and sending
> symbol for renaming, but we do that only for live statements, so we skip
> the dead stmt. ?When removing the dead stmt we compensate by replacing
> operands of live stmt by vuse patching back the dead stmt.
>
> THe patch simply sends for updaiting all uses, dead or alive. ?It woudl
> be also possible to do more work and do updating only in scenario
> described above.
>
> Bootstrapped/regtested x86_64-linux, OK?
>
> struct S0 {
> ?signed char f0;
> ?signed char f4;
> };
>
> struct S0 g_19 = {
> ?7L, 0L
> };
>
> struct S0 g_39 = {
> ?0L, 0x49L
> };
>
> struct S0 g_90 = {
> ?1L, 0
> };
>
> signed char g_125;
> signed char g_198;
> signed char g_218;
>
> signed char func_17 (int p_18, struct S0 p_20, signed char p_22, signed char
> p_24)
> {
> ?return p_20.f0;
> }
>
> signed char func_61 (int p_63, signed char p_64, signed char p_65)
> {
> ?return 0;
> }
>
> struct S0 func_176 (int p_178, int p_179)
> {
> ?return g_90;
> }
>
> struct S0 func_160 (int p_161, int p_163)
> {
> ?struct S0 l_240 = {
> ? ?9L, 0L
> ?};
> ?if (func_17 (1, func_176 (g_218, 1), 1, 1))
> ? ?{
> ? ? ?struct S0 l_253 = {
> ? ? ? ?0xE0, 0xB4L
> ? ? ?};
> ? ? ?return l_253;
> ? ?}
> ?return l_240;
> }
>
> struct S0 func_150 (int p_151, signed char p_153, signed char p_154, signed
> char p_155)
> {
> ?signed char l_156 = 0;
> ?signed char l_266 = 0;
> ?if (func_17
> ? ? ?(func_61
> ? ? ? (g_125, l_156,
> ? ? ? ?func_61 (1, func_17 (1, func_160 (l_266, g_90.f4), p_153, 1), 1)),
> ? ? ? func_176 (g_39.f0, 1), 1, 1))
> ? ?{
> ? ? ?g_198 = 1;
> ? ?}
> ?return g_19;
> }
> ? ? ? ?PR tree-optimization/40759
> ? ? ? ?* tree-ssa-dce.c (mark_virtual_phi_result_for_renaming): Mark all uses
> ? ? ? ?for renaming.

Shouldn't we include the testcase?

Thanks.


-- 
H.J.