[PATCH, i386]: Fix PR 57106, -fcompare-debug failure with -O2 -fschedule-insns -funroll-all-loops

[Uros Bizjak]

Hello!

Apparently, the wrong insn is used when adding insn dependencies. The
"last" index gets updated to the found !NONDEBUG_INSN. Use "first_arg"
that points to the right insn instead.

2013-05-03  Uros Bizjak  <ubiz...@gmail.com>

    PR target/57106
    * config/i386/i386.c (add_parameter_dependencies): Add dependence
    between "first_arg" and "insn", not "last" and "insn".

testsuite/ChangeLog:

2013-05-03  Uros Bizjak  <ubiz...@gmail.com>

    * gcc.target/i386/pr57106.c: New test.

Tested on x86_64-pc-linux-gnu {,-m32}. I will wait for Intel guys to
check this patch with -fschedule-insns on their codes.

Uros.

Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c  (revision 198577)
+++ config/i386/i386.c  (working copy)
@@ -24662,7 +24662,7 @@ add_parameter_dependencies (rtx call, rtx head)
          /* Add output depdendence between two function arguments if chain
             of output arguments contains likely spilled HW registers.  */
          if (is_spilled)
-           add_dependence (last, insn, REG_DEP_OUTPUT);
+           add_dependence (first_arg, insn, REG_DEP_OUTPUT);
          first_arg = last = insn;
        }
       else
@@ -41355,7 +41355,8 @@ ix86_enum_va_list (int idx, const char **pname, tr
 #undef TARGET_SCHED_ADJUST_PRIORITY
 #define TARGET_SCHED_ADJUST_PRIORITY ix86_adjust_priority
 #undef TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK
-#define TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK 
ix86_dependencies_evaluation_hook
+#define TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK \
+  ix86_dependencies_evaluation_hook
 
 /* The size of the dispatch window is the total number of bytes of
    object code allowed in a window.  */
Index: testsuite/gcc.target/i386/pr57106.c
===================================================================
--- testsuite/gcc.target/i386/pr57106.c (revision 0)
+++ testsuite/gcc.target/i386/pr57106.c (working copy)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fschedule-insns -funroll-all-loops -fcompare-debug" } */
+
+typedef void block128_f (int *, int);
+
+void
+foo (int *out, int *iv, block128_f block)
+{
+  while (1)
+    {
+      *out = *out ^ *iv;
+      block (out, *out);
+      iv = out;
+    }
+}