--- wikisrc/users/maya/vax-gcc.mdwn	2019/08/29 12:43:34	1.1
+++ wikisrc/users/maya/vax-gcc.mdwn	2019/08/30 02:09:23	1.8
@@ -1,23 +1,70 @@
 # Various GCC/vax issues and invesigation #
 
-# libgomp crash with -O2 #
+[WIP tree](gcc-mirror/)
+
+## libgomp crash with -O2 ##
 Repro:
-````
-#!/bin/sh
 
-cat << EOF > oacc.i
-int a, b;
-int e() {
-  short *c = 0;
-  char d = c[a + 1];
-  b = d;
-  a += 2;
-}
-EOF
-vax--netbsdelf-gcc -O2 -c oacc.i
-````
+    #!/bin/sh
+    
+    cat << EOF > oacc.i
+    int a, b;
+    int e() {
+      short *c = 0;
+      char d = c[a + 1];
+      b = d;
+      a += 2;
+    }
+    EOF
+    vax--netbsdelf-gcc -O2 -c oacc.i
+
 Asserts at emit-rtl.c:2310 gcc_assert (memory_address_addr_space_p (mode, addr, as));
 
-NetBSD avoids it with a local diff to reload.c/dse.c.
+NetBSD avoids it with a [local diff](https://github.com/NetBSD/src/commit/e437e96750193b86d0464965661f616e011056fa) to reload.c/dse.c.  
+It looks like a real bug in vax_legitimate_address_p not handling some addressing modes.  
+The code to handle offset(reg)[index] might be off: it doesn't like if neither xfoo0, xfoo1 are constant.
+
+## unrecognizable insn with any optimization ##
+
+Repro:
+
+    #!/bin/sh
+
+    cat << EOF > decl.ii
+    struct a {
+      long long *b() const;
+    };
+    template <typename> class d : a {
+    public:
+      template <typename e> d(e);
+      long long f() const;
+    };
+    template <typename c> long long d<c>::f() const {
+      int g;
+      return b()[g];
+    }
+    int h;
+    bool i() {
+      d<int> j(h);
+      return j.f();
+    }
+    EOF
+    vax--netbsdelf-g++ -O2 -c decl.ii
+
+This errors out with:
 
-It looks like a real bug in vax_legitimate_address_p not handling some addressing modes
+    $ env PATH=$PWD:$PATH ./xgcc -fno-use-linker-plugin -c -O2 ~/oacc/decl.ii -fno-tree-vectorize
+    /home/fly/oacc/decl.ii: In function 'bool i()':
+    /home/fly/oacc/decl.ii:17:1: error: unrecognizable insn:
+       17 | }
+          | ^
+    (insn 13 12 14 2 (set (reg:SI 33)
+            (subreg:SI (mem:DI (plus:SI (mult:SI (reg/v:SI 24 [ g ])
+                            (const_int 8 [0x8]))
+                        (reg/f:SI 23 [ _6 ])) [1 *_10+0 S8 A32]) 4)) "/home/fly/oacc/decl.ii":16:14 -1
+         (nil))
+    during RTL pass: vregs
+    /home/fly/oacc/decl.ii:17:1: internal compiler error: in extract_insn, at recog.c:2310
+    
+Providing a trivial scheduling will avoid subregs of mem.  
+However, this doesn't work for us. Our crash and mem subregs happen at a too early pass, most likely.