1: # Various GCC/vax issues and invesigation #
2:
3: [WIP tree](gcc-mirror/)
4:
5: ## libgomp crash with -O2 [#58901](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58901) ##
6: Repro:
7:
8: #!/bin/sh
9:
10: cat << EOF > oacc.i
11: int a, b;
12: int e() {
13: short *c = 0;
14: char d = c[a + 1];
15: b = d;
16: a += 2;
17: }
18: EOF
19: vax--netbsdelf-gcc -O2 -c oacc.i
20:
21: Asserts at emit-rtl.c:2310 gcc_assert (memory_address_addr_space_p (mode, addr, as));
22:
23: NetBSD avoids it with a [local diff](https://github.com/NetBSD/src/commit/e437e96750193b86d0464965661f616e011056fa) to reload.c/dse.c.
24: It looks like a real bug in vax_legitimate_address_p not handling some addressing modes.
25: The code to handle offset(reg)[index] might be off: it doesn't like if neither xfoo0, xfoo1 are constant.
26:
27:
28: ## change_address_1, at emit-rtl.c:2286 [#85152](https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85152) ##
29:
30: Repro:
31:
32: #!/bin/sh
33:
34: cat << EOF > oacc.i
35: void fn2();
36: unsigned a;
37: int fn1() {
38: int b = a >> 16;
39: if (b)
40: fn2();
41: }
42: EOF
43: vax--netbsdelf-gcc -O2 -c oacc.i
44:
45: ## unrecognizable insn with any optimization ##
46:
47: Repro:
48:
49: #!/bin/sh
50:
51: cat << EOF > decl.ii
52: struct a {
53: long long *b() const;
54: };
55: template <typename> class d : a {
56: public:
57: template <typename e> d(e);
58: long long f() const;
59: };
60: template <typename c> long long d<c>::f() const {
61: int g;
62: return b()[g];
63: }
64: int h;
65: bool i() {
66: d<int> j(h);
67: return j.f();
68: }
69: EOF
70: vax--netbsdelf-g++ -O2 -c decl.ii
71:
72: This errors out with:
73:
74: $ env PATH=$PWD:$PATH ./xgcc -fno-use-linker-plugin -c -O2 ~/oacc/decl.ii -fno-tree-vectorize
75: /home/fly/oacc/decl.ii: In function 'bool i()':
76: /home/fly/oacc/decl.ii:17:1: error: unrecognizable insn:
77: 17 | }
78: | ^
79: (insn 13 12 14 2 (set (reg:SI 33)
80: (subreg:SI (mem:DI (plus:SI (mult:SI (reg/v:SI 24 [ g ])
81: (const_int 8 [0x8]))
82: (reg/f:SI 23 [ _6 ])) [1 *_10+0 S8 A32]) 4)) "/home/fly/oacc/decl.ii":16:14 -1
83: (nil))
84: during RTL pass: vregs
85: /home/fly/oacc/decl.ii:17:1: internal compiler error: in extract_insn, at recog.c:2310
86:
87:
88: This is in VAX-specific code. We need to figure out what instruction pattern this is, that we're missing.
89:
90: <!--Providing a trivial scheduling will avoid subregs of mem.
91: However, this doesn't work for us. Our crash and mem subregs happen at a too early pass, most likely.-->
92:
93: ## DWARF ##
94:
95: flag_dwarf2_cfi_asm = 0;
96:
97: is kind of a big deal. We should probably get rid of it, but [binutils hates that.](https://github.com/NetBSD/src/commit/1df57dce3744cf4743358b098728a0658b80b8fb)
98:
99: ld: warning: dynamic relocation to `?' in readonly section `.eh_frame'
100: ld: warning: dynamic relocation to `?' in readonly section `.eh_frame'
101: ld: warning: creating a DT_TEXTREL in a shared object
102: ld: .eh_frame_hdr refers to overlapping FDEs
103: ld: final link failed: bad value
104:
105: [riscv seemed to share the issue](https://github.com/riscv/riscv-binutils-gdb/issues/76) and had fixed it.
106:
107: ## review comments ##
108:
109: Jeff Law [provided some feedback](https://gcc.gnu.org/ml/gcc/2019-04/msg00281.html). More of it should be addressed.
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