[Bug tree-optimization/100774] New: [12 Regression] -fcompare-debug failure (length) with -O2 -fno-tree-forwprop --param=evrp-mode=ranger-trace

[zsojka at seznam dot cz via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100774

            Bug ID: 100774
           Summary: [12 Regression] -fcompare-debug failure (length) with
                    -O2 -fno-tree-forwprop --param=evrp-mode=ranger-trace
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
                CC: aoliva at gcc dot gnu.org
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu

Created attachment 50872
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50872&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-g++ -O2 -fno-tree-forwprop --param=evrp-mode=ranger-trace
-fcompare-debug testcase.C
x86_64-pc-linux-gnu-g++: error: testcase.C: '-fcompare-debug' failure (length)
$ diff -u *gkd
--- a-testcase.C.gkd    2021-05-26 17:07:09.776753885 +0200
+++ a-testcase.gk.C.gkd 2021-05-26 17:07:09.856753886 +0200
@@ -1,31 +1,15 @@

-Declarations used by foo, sorted by DECL_UID:
-0:   extern void error (void);

 ;; Function foo (_Z3foov, funcdef_no=1, cgraph_uid=2, symbol_order=2)
(executed once)

 (note # 0 0 NOTE_INSN_DELETED)
-(note # 0 0 [bb 2] NOTE_INSN_BASIC_BLOCK)
 (note # 0 0 NOTE_INSN_FUNCTION_BEG)
-(insn/f:TI # 0 0 2 (parallel [
-            (set (reg/f:DI 7 sp)
-                (plus:DI (reg/f:DI 7 sp)
-                    (const_int -8 [0xfffffffffffffff8])))
-            (clobber (reg:CC 17 flags))
-            (clobber (mem:BLK (scratch) [  A8]))
-        ]) "testcase.C":12:1# {pro_epilogue_adjust_stack_add_di}
-     (expr_list:REG_UNUSED (reg:CC 17 flags)
-        (expr_list:REG_CFA_ADJUST_CFA (set (reg/f:DI 7 sp)
-                (plus:DI (reg/f:DI 7 sp)
-                    (const_int -8 [0xfffffffffffffff8])))
-            (nil))))
 (note # 0 0 NOTE_INSN_PROLOGUE_END)
-(call_insn:TI # 0 0 2 (call (mem:QI (symbol_ref:DI ("_Z5errorv") [flags 0x41] 
<function_decl # error>) [ error S1 A8])
-        (const_int 0 [0])) "testcase.C":19:12# {*call}
-     (expr_list:REG_CALL_DECL (symbol_ref:DI ("_Z5errorv") [flags 0x41] 
<function_decl # error>)
-        (expr_list:REG_ARGS_SIZE (const_int 0 [0])
-            (expr_list:REG_NORETURN (const_int 0 [0])
-                (nil))))
-    (nil))
+(code_label # 0 0 2 2 (nil) [1 uses])
+(note # 0 0 [bb 2] NOTE_INSN_BASIC_BLOCK)
+(jump_insn:TI # 0 0 2 (set (pc)
+        (label_ref #))# {jump}
+     (nil)
+ -> 2)
 (barrier # 0 0)
 (note # 0 0 NOTE_INSN_DELETED)