------- Comment #6 from ubizjak at gmail dot com 2008-09-17 08:14 ------- cprop_hardreg pass is propagating DImode ax register, wrongly bypassing DI-SI conversion.
Before cprop_hardreg, we have: (call_insn/u:HI 27 88 28 4 pr37544.c:9 (set (reg:DI 0 ax) (call (mem:QI (symbol_ref:SI ("__fixunsdfdi") [flags 0x41]) [0 S1 A8]) (const_int 16 [0x10]))) 687 {*call_value_0} (expr_list:REG_UNUSED (reg:SI 1 dx) (expr_list:REG_EH_REGION (const_int -1 [0xffffffff]) (nil))) (expr_list:REG_DEP_TRUE (use (mem:DF (plus:SI (reg/f:SI 7 sp) (scratch:SI)) [0 S8 A8])) (nil))) (insn 95 28 104 4 pr37544.c:9 (set (reg:SI 21 xmm0) (reg:SI 0 ax [78])) 41 {*movsi_1} (expr_list:REG_DEAD (reg:SI 0 ax [78]) (nil))) (insn 104 95 105 4 pr37544.c:9 (set (mem/c:DI (plus:SI (reg/f:SI 6 bp) (const_int -8032 [0xffffe0a0])) [0 S8 A64]) (reg:DI 21 xmm0)) 63 {*movdi_2} (expr_list:REG_DEAD (reg:DI 21 xmm0) (nil))) (insn 105 104 89 4 pr37544.c:9 (set (reg/v:DF 8 st [orig:65 b ] [65]) (float:DF (mem/c:DI (plus:SI (reg/f:SI 6 bp) (const_int -8032 [0xffffe0a0])) [0 S8 A64]))) 179 {*floatdidf2_i387} (nil)) and after cprop_hardreg: (call_insn/u:HI 27 88 28 4 pr37544.c:9 (set (reg:DI 0 ax) (call (mem:QI (symbol_ref:SI ("__fixunsdfdi") [flags 0x41]) [0 S1 A8]) (const_int 16 [0x10]))) 687 {*call_value_0} (expr_list:REG_UNUSED (reg:SI 1 dx) (expr_list:REG_EH_REGION (const_int -1 [0xffffffff]) (nil))) (expr_list:REG_DEP_TRUE (use (mem:DF (plus:SI (reg/f:SI 7 sp) (scratch:SI)) [0 S8 A8])) (nil))) (insn 95 28 104 4 pr37544.c:9 (set (reg:SI 21 xmm0) (reg:SI 0 ax [78])) 41 {*movsi_1} (expr_list:REG_DEAD (reg:SI 0 ax [78]) (nil))) (insn 104 95 105 4 pr37544.c:9 (set (mem/c:DI (plus:SI (reg/f:SI 6 bp) (const_int -8032 [0xffffe0a0])) [0 S8 A64]) (reg:DI 0 ax [21])) 63 {*movdi_2} (expr_list:REG_DEAD (reg:DI 21 xmm0) (nil))) (insn 105 104 89 4 pr37544.c:9 (set (reg/v:DF 8 st [orig:65 b ] [65]) (float:DF (mem/c:DI (plus:SI (reg/f:SI 6 bp) (const_int -8032 [0xffffe0a0])) [0 S8 A64]))) 179 {*floatdidf2_i387} (nil)) Please note, how DImode ax reg propagates into (insn 104), bypassing SImode conversion in (insn 95). -- ubizjak at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- Component|target |rtl-optimization Priority|P3 |P1 Summary|Conversion double -> |[4.2/4.3/4.4 Regression] |unsigned long long -> |Conversion double -> |unsigned -> double gives |unsigned long long -> |wrong results |unsigned -> double gives | |wrong results Target Milestone|--- |4.2.5 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37544