Bug 88845 - ICE in lra_set_insn_recog_data, at lra.c:1010
Summary: ICE in lra_set_insn_recog_data, at lra.c:1010
Status: RESOLVED FIXED
Alias: None
Product: gcc
Classification: Unclassified
Component: rtl-optimization (show other bugs)
Version: 9.0
: P3 normal
Target Milestone: ---
Assignee: Peter Bergner
URL: https://gcc.gnu.org/ml/gcc-patches/20...
Keywords:
Depends on:
Blocks:
 
Reported: 2019-01-14 17:41 UTC by Peter Bergner
Modified: 2019-03-06 15:39 UTC (History)
5 users (show)

See Also:
Host:
Target: powerpc64*-linux
Build:
Known to work:
Known to fail:
Last reconfirmed:

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Description Peter Bergner 2019-01-14 17:41:16 UTC 
The following ICEs for me with trunk, GCC 8 and GCC 7:

bergner@pike:~$ cat bug.i
struct a {
  unsigned b;
  float c;
};
void
foo (void)
{
  float e;
  struct a f;
  e = f.c;
  __asm__("" : : "f"(e));
}
bergner@pike:~$ gcc -O2 -S bug.i
bug.i: In function ‘foo’:
bug.i:12:1: internal compiler error: in lra_set_insn_recog_data, at lra.c:1010
 }
 ^
Comment 1 Peter Bergner 2019-01-14 18:01:20 UTC 
After IRA, we have the following RTL with pseudo 124 being assigned to r9, which does not meet the "f" constraint required by the inline asm:

(insn 6 5 7 2 (set (reg:SI 124)
        (const_int 0 [0])) "pr88845.i":10:5 494 {*movsi_internal1}
     (expr_list:REG_EQUIV (const_int 0 [0])
        (nil)))
(insn 7 6 12 2 (parallel [
            (asm_operands/v ("") ("") 0 [
                    (subreg:SF (reg:SI 124) 0)
                ]
                 [
                    (asm_input:SF ("f") pr88845.i:11)
                ]
                 [] pr88845.i:11)
            (clobber (reg:SI 76 ca))
        ]) "pr88845.i":11:3 -1
     (expr_list:REG_DEAD (reg:SI 124)
        (expr_list:REG_UNUSED (reg:SI 76 ca)
            (nil))))

LRA then generates the following:

(insn 6 5 14 2 (set (reg:SI 124)
        (const_int 0 [0])) "pr88845.i":10:5 494 {*movsi_internal1}
     (expr_list:REG_EQUIV (const_int 0 [0])
        (nil)))
(insn 14 6 7 2 (set (reg:SF 125)
        (subreg:SF (reg:SI 124) 0)) "pr88845.i":11:3 -1
     (nil))
(insn 7 14 12 2 (parallel [
            (asm_operands/v ("") ("") 0 [
                    (reg:SF 125)
                ]
                 [
                    (asm_input:SF ("f") pr88845.i:11)
                ]
                 [] pr88845.i:11)
            (clobber (reg:SI 76 ca))
        ]) "pr88845.i":11:3 -1
     (expr_list:REG_DEAD (reg:SI 124)
        (expr_list:REG_UNUSED (reg:SI 76 ca)
            (nil))))

...and we ICE in lra_set_insn_recog_data when handling the reload insn 14.
Comment 2 Peter Bergner 2019-01-14 21:14:42 UTC 
Thinking about this, insn 14 doesn't look legal to me for ppc, since FP values in our FP regs are actually stored as 64-bit quantities, even for SFmode, so copying a 32-bit SImode value over to a 64-bit wide reg holding a SFmode value doesn't make sense, correct?
Comment 3 Segher Boessenkool 2019-01-17 15:08:50 UTC 
(In reply to Peter Bergner from comment #2)
> Thinking about this, insn 14 doesn't look legal to me for ppc, since FP
> values in our FP regs are actually stored as 64-bit quantities, even for
> SFmode, so copying a 32-bit SImode value over to a 64-bit wide reg holding a
> SFmode value doesn't make sense, correct?

It looks fine to me?  It may need going via memory to implement, but it is
a valid construct?
Comment 4 Peter Bergner 2019-03-06 15:37:18 UTC 
Author: bergner
Date: Wed Mar  6 15:36:43 2019
New Revision: 269428

URL: https://gcc.gnu.org/viewcvs?rev=269428&root=gcc&view=rev
Log:
gcc/
	PR rtl-optimization/88845
	* config/rs6000/rs6000.c (rs6000_emit_move_si_sf_subreg): Enable during
	LRA.
	* lra.c (remove_scratches_1): New function.
	(remove_scratches): Use it.
	(lra_emit_move): Likewise.

gcc/testsuite/
	PR rtl-optimization/88845
	* gcc.target/powerpc/pr88845.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/powerpc/pr88845.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/rs6000/rs6000.c
    trunk/gcc/lra.c
    trunk/gcc/testsuite/ChangeLog
Comment 5 Peter Bergner 2019-03-06 15:39:12 UTC 
Fixed with the LRA version of the patch linked above.