Hi, I have a regression w.r.t subreg expression in reload phase for the recently posted cr16 patch . (http://gcc.gnu.org/ml/gcc-patches/2011-04/msg00624.html). Since the CR16 port has multiple width registers I am facing quite a few problems related to subreg expressions. Though I addressed most of the issues and I found a regression with optimization (-On) in gcc.c-torture/compile/ and the test case is ptr-conv-1.c. GCC version used : 4.5.1 The test case is : long long a; void f (void) { int c = 1; volatile int *p = &c; a = (long long) (__PTRDIFF_TYPE__) p; *p; } and the output at command prompt looks like $ build/gcc/gcc/cc1 ptr-conv-1.c -O f Analyzing compilation unit Performing interprocedural optimizations <*free_lang_data> <visibility> <early_local_cleanups> <whole-program> <inline> <static-var> <pure-const>Assembling functions: f ptr-conv-1.c: In function 'f': ptr-conv-1.c:11:1: internal compiler error: in gen_rtx_SUBREG, at emit-rtl.c:776 Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. After debugging this for a while I figured it out the issue due to reload. The rtl dump for the above test case is ptr-conv-1.c.141r.expand: ___________________________ insn 6 5 7 3 ptr-conv-1.c:7 (set (mem/c/i:HI (reg/f:SI 17 virtual-stack-vars) [0 c+0 S2 A32]) (const_int 1 [0x1])) -1 (nil)) (insn 7 6 8 3 ptr-conv-1.c:8 (set (reg/v/f:SI 21 [ p ]) (reg/f:SI 17 virtual-stack-vars)) -1 (nil)) (insn 8 7 9 3 ptr-conv-1.c:9 (set (reg/f:SI 26) (symbol_ref:SI ("a") <var_decl 0xb8019000 a>)) -1 (nil)) (insn 9 8 10 3 ptr-conv-1.c:9 (set (mem/c/i:SI (reg/f:SI 26) [0 a+0 S4 A32]) (reg/v/f:SI 21 [ p ])) -1 (nil)) (insn 10 9 11 3 ptr-conv-1.c:9 (set (reg:HI 28) (ashiftrt:HI (subreg:HI (reg/v/f:SI 21 [ p ]) 2) (const_int 15 [0xf]))) -1 (nil)) (insn 11 10 12 3 ptr-conv-1.c:9 (set (mem/c/i:HI (const:SI (plus:SI (symbol_ref:SI ("a") <var_decl 0xb8019000 a>) (const_int 4 [0x4]))) [0 a+4 S2 A32]) (reg:HI 28)) -1 (nil)) (insn 12 11 13 3 ptr-conv-1.c:9 (set (mem/c/i:HI (const:SI (plus:SI (symbol_ref:SI ("a") <var_decl 0xb8019000 a>) (const_int 6 [0x6]))) [0 a+6 S2 A16]) (reg:HI 28)) -1 (nil)) (insn 13 12 14 3 ptr-conv-1.c:10 (set (reg:HI 24 [ vol.2 ]) (mem/v:HI (reg/v/f:SI 21 [ p ]) [0 S2 A16])) -1 (nil)) ptr-conv-1.c.185r.asmcons: __________________________ (insn 6 3 9 2 ptr-conv-1.c:7 (set (mem/c/i:HI (reg/f:SI 13 r13) [0 c+0 S2 A32]) (const_int 1 [0x1])) 66 {*movhi_short} (nil)) (insn 9 6 10 2 ptr-conv-1.c:9 (set (mem/c/i:SI (symbol_ref:SI ("a") <var_decl 0xb8019000 a>) [0 a+0 S4 A32]) (reg/f:SI 13 r13)) 63 {*movsi_long} (nil)) (insn 10 9 11 2 ptr-conv-1.c:9 (set (reg:HI 28) (ashiftrt:HI (subreg:HI (reg/f:SI 13 r13) 2) (const_int 15 [0xf]))) 44 {ashrhi3_imm_insn} (nil)) (insn 11 10 12 2 ptr-conv-1.c:9 (set (mem/c/i:HI (const:SI (plus:SI (symbol_ref:SI ("a") <var_decl 0xb8019000 a>) (const_int 4 [0x4]))) [0 a+4 S2 A32]) (reg:HI 28)) 66 {*movhi_short} (nil)) (insn 12 11 13 2 ptr-conv-1.c:9 (set (mem/c/i:HI (const:SI (plus:SI (symbol_ref:SI ("a") <var_decl 0xb8019000 a>) (const_int 6 [0x6]))) [0 a+6 S2 A16]) (reg:HI 28)) 66 {*movhi_short} (expr_list:REG_DEAD (reg:HI 28) (nil))) (insn 13 12 0 2 ptr-conv-1.c:10 (set (reg:HI 24 [ vol.2 ]) (mem/v:HI (reg/f:SI 13 r13) [0 S2 A16])) 66 {*movhi_short} (expr_list:REG_UNUSED (reg:HI 24 [ vol.2 ]) (nil))) Back trace for the ICE: ________________________ gen_rtx_SUBREG (mode=HImode, reg=0xb7ef4240, offset=2) at /home/sumanth/v105/src/gcc-4.5.1/gcc/emit-rtl.c:776 #1 0x083557c1 in eliminate_regs_1 (x=0xb7ef5e04, mem_mode=VOIDmode, insn=0x0, may_use_invariant=0 '\0') at /home/sumanth/v105/src/gcc-4.5.1/gcc/reload1.c:2863 #2 0x0835684c in eliminate_regs_in_insn (insn=0xb7f4b57c, replace=0) at /home/sumanth/v105/src/gcc-4.5.1/gcc/reload1.c:3466 #3 0x0835303c in calculate_needs_all_insns (global=1) at /home/sumanth/v105/src/gcc-4.5.1/gcc/reload1.c:1651 #4 0x08351bc5 in reload (first=0xb7efb5e0, global=1) at /home/sumanth/v105/src/gcc-4.5.1/gcc/reload1.c:1073 #5 0x082a6869 in ira (f=0x87e5b30) at /home/sumanth/v105/src/gcc-4.5.1/gcc/ira.c:3315 #6 0x082a6b9b in rest_of_handle_ira () at /home/sumanth/v105/src/gcc-4.5.1/gcc/ira.c:3387 #7 0x0830c31e in execute_one_pass (pass=0x8762f20) at /home/sumanth/v105/src/gcc-4.5.1/gcc/passes.c:1568 #8 0x0830c602 in execute_pass_list (pass=0x8762f20) at /home/sumanth/v105/src/gcc-4.5.1/gcc/passes.c:1623 ........................................................................................................ ........................................................................................................ Conclusion: ___________ The test case passes if run with "-O1 -fno-omit-frame-pointer". The subreg in ashift is the cause for ICE. Specially the subreg byte (value of 2) triggers the ICE. (insn 10 9 11 2 ptr-conv-1.c:9 (set (reg:HI 28) (ashiftrt:HI (subreg:HI (reg/f:SI 13 r13) 2) (const_int 15 [0xf]))) 44 {ashrhi3_imm_insn} (nil)) is converted to (insn 10 9 11 2 ptr-conv-1.c:9 (set (reg:HI 28) (ashiftrt:HI (subreg:HI (reg/f:SI 15 r15) 2) (const_int 15 [0xf]))) 44 {ashrhi3_imm_insn} (nil)) Since the pattern supports only short regs, r15 was reloaded with r0. It was only during this phase , cc1 hits ICE. I have been working on this issue for quite some time. Any help in this issue is highly appreciated. Thanks in advance, Sumanth G
