James Greenhalgh <james.greenha...@arm.com> writes:
> This seems to have caused PR58373. The bug occurs where GEN_INT would
> previously have then been used to build a constant of vector mode.
>
> These pop in a few places when building for AArch64, though I did
> the debugging using gcc.target/aarch64/vect-fcm-eq-d.c
>
> Here we could get in to the situation where
> simplify_unary_expression_1 would see (V2DI: NOT (NEG X))
> and try to generate (V2DI: PLUS (X - 1)). In turn, we would reach the
> call in plus_constant to gen_int_mode (-1, v2di), followed by
> trunc_int_for_mode (-1, v2di) and this assert would trigger:
>
> /* You want to truncate to a _what_? */
> gcc_assert (SCALAR_INT_MODE_P (mode));
>
> In this fix I catch the case where gen_int_mode has been asked to
> build a vector mode, and call trunc_int_for_mode on the inner mode
> of that vector. A similar fix could sit in trunc_int_for_mode if
> you would prefer.
>
> Bootstrapped on x86_64-unknown-linux-gnu with no issues and regression
> tested for aarch64-none-elf with the expected benefits and no regressions.
Sorry for the breakage. gen_int_mode and GEN_INT really are only for
scalar integers though. (So is plus_constant.) Vector constants should
be CONST_VECTORs rather than CONST_INTs.
I think the gcc.target/aarch64/vect-fcm-eq-d.c failure is from a latent
bug in the way (neg (not ...)) and (not (neg ...)) are handled.
Could you give the attached patch a go?
I looked through the other calls to plus_constant in simplify-rtx.c,
but they seem OK.
Thanks,
Richard
gcc/
* simplify-rtx.c (simplify_unary_operation_1): Use simplify_gen_binary
for (not (neg ...)) and (neg (not ...)) casees.
Index: gcc/simplify-rtx.c
===================================================================
--- gcc/simplify-rtx.c 2013-09-10 20:02:08.756091875 +0100
+++ gcc/simplify-rtx.c 2013-09-10 20:02:09.002093907 +0100
@@ -825,7 +825,8 @@ simplify_unary_operation_1 (enum rtx_cod
/* Similarly, (not (neg X)) is (plus X -1). */
if (GET_CODE (op) == NEG)
- return plus_constant (mode, XEXP (op, 0), -1);
+ return simplify_gen_binary (PLUS, mode, XEXP (op, 0),
+ CONSTM1_RTX (mode));
/* (not (xor X C)) for C constant is (xor X D) with D = ~C. */
if (GET_CODE (op) == XOR
@@ -932,7 +933,8 @@ simplify_unary_operation_1 (enum rtx_cod
/* Similarly, (neg (not X)) is (plus X 1). */
if (GET_CODE (op) == NOT)
- return plus_constant (mode, XEXP (op, 0), 1);
+ return simplify_gen_binary (PLUS, mode, XEXP (op, 0),
+ CONST1_RTX (mode));
/* (neg (minus X Y)) can become (minus Y X). This transformation
isn't safe for modes with signed zeros, since if X and Y are
