[Bug target/59379] [4.9 Regression] gomp_init_num_threads is compiled into an infinite loop with --with-arch=corei7 --with-cpu=slm

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59379

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ubizjak at gmail dot com

--- Comment #15 from H.J. Lu <hjl.tools at gmail dot com> ---
The problem is in ix86_split_lea_for_addr.  For LEA operation with
SImode_address_operand, which zero-extends SImode to DImode, it turns

(set (reg:DI) ...)

into

(set (reg:SI) ...)

We need to do

(set (reg:DI) (zero_extend:DI (reg:SI)))

at the end:

---
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index ff210c8..5ceccdf 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -18375,7 +18375,7 @@ ix86_split_lea_for_addr (rtx insn, rtx operands[], enum
machine_mode mode)
         ix86_emit_binop (PLUS, mode, target, parts.disp);

           ix86_emit_binop (PLUS, mode, target, tmp1);
-          return;
+          goto check_mode;
         }

       ix86_emit_binop (PLUS, mode, target, tmp);
@@ -18384,6 +18384,13 @@ ix86_split_lea_for_addr (rtx insn, rtx operands[],
enum machine_mode mode)
       if (parts.disp && parts.disp != const0_rtx)
     ix86_emit_binop (PLUS, mode, target, parts.disp);
     }
+
+check_mode:
+  if (mode != GET_MODE (operands[0]))
+    {
+      gcc_assert (mode == SImode && GET_MODE (operands[0]) == DImode);
+      emit_insn (gen_zero_extendsidi2 (operands[0], target));
+    }
 }

 /* Return true if it is ok to optimize an ADD operation to LEA
---

Or we can avoid splitting LEA for SImode_address_operand by

---
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 954bbed..e5e6e12 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -5415,10 +5415,11 @@
   else 
     return "lea{<imodesuffix>}\t{%E1, %0|%0, %E1}";
 }
-  "reload_completed && ix86_avoid_lea_for_addr (insn, operands)" 
+  "reload_completed
+   && !SImode_address_operand (operands[1], VOIDmode)
+   && ix86_avoid_lea_for_addr (insn, operands)" 
   [(const_int 0)]
 {
-  enum machine_mode mode = <MODE>mode;
   rtx pat;

   /* ix86_avoid_lea_for_addr re-recognizes insn and may
@@ -5428,12 +5429,7 @@
   operands[0] = SET_DEST (pat);
   operands[1] = SET_SRC (pat);

-  /* Emit all operations in SImode for zero-extended addresses.  Recall
-     that x86_64 inheretly zero-extends SImode operations to DImode.  */
-  if (SImode_address_operand (operands[1], VOIDmode))
-    mode = SImode;
-
-  ix86_split_lea_for_addr (curr_insn, operands, mode);
+  ix86_split_lea_for_addr (curr_insn, operands, <MODE>mode);
   DONE;
 }
   [(set_attr "type" "lea")
---

Either patch fixes the problem.