Re: Problem exposed by recent ARM multiply changes

[Richard Earnshaw (lists)]

On 26/09/2019 07:49, Jakub Jelinek wrote:

On Wed, Sep 25, 2019 at 10:06:13PM -0600, Jeff Law wrote:

(insn 13 12 14 2 (set (reg:SI 124)
         (const_int -939524096 [0xffffffffc8000000])) "j.c":10:54 161
{*arm_movsi_insn}
      (nil))

(insn 14 13 16 2 (parallel [
             (set (reg:SI 132)
                 (plus:SI (mult:SI (zero_extend:DI (reg/v:SI 115 [ sec ]))
                         (zero_extend:DI (reg:SI 124)))
                     (reg:SI 130)))

IMNSHO the bug is just in the backend, the above is not valid RTL.
SImode MULT has to have SImode operands, not DImode operands.

             (set (reg:SI 133 [+4 ])
                 (plus:SI (truncate:SI (lshiftrt:DI (plus:DI (mult:DI
(zero_extend:DI (reg/v:SI 115 [ sec ]))
                                     (zero_extend:DI (reg:SI 124)))
                                 (zero_extend:DI (reg:SI 130)))
                             (const_int 32 [0x20])))
                     (reg:SI 131 [+4 ])))

 From the rest of the pattern, I'd say the right fix is just to:
--- gcc/config/arm/arm.md.jj    2019-09-20 23:17:28.786629241 +0200
+++ gcc/config/arm/arm.md       2019-09-26 08:47:40.068517793 +0200
@@ -1812,8 +1812,8 @@
    [(set (match_operand:SI 0 "s_register_operand" "=r,&r")
        (plus:SI
         (mult:SI
-         (SE:DI (match_operand:SI 4 "s_register_operand" "%r,r"))
-         (SE:DI (match_operand:SI 5 "s_register_operand" "r,r")))
+         (match_operand:SI 4 "s_register_operand" "%r,r")
+         (match_operand:SI 5 "s_register_operand" "r,r"))
         (match_operand:SI 1 "s_register_operand" "0,0")))
     (set (match_operand:SI 2 "s_register_operand" "=r,&r")
        (plus:SI
because it really only cares about the DImode zext values in the second part
of the instruction, but I don't have spare cycles to test this right now nor
write testcases.

        Jakub

Yes, this looks like a simple cut-and-paste error.  This patch is approved.

R.