On Wed, May 05, 2021 at 07:44:46PM +0200, Jakub Jelinek via Gcc-patches wrote:
> So perhaps just the vd->e[dr].mode in there could change to
> GET_MODE (src) and drop the previous PR98694 change?
I've bootstrapped/regtested that successfully on the trunk
(on {x86_64,i686}-linux), though haven't attempted to merge the two comments:
2021-05-06 Jakub Jelinek <ja...@redhat.com>
PR rtl-optimization/100342
* regcprop.c (copy_value): When copying a source reg in a wider
mode than it has recorded for the value, adjust recorded destination
mode too.
* gcc.target/i386/pr100342.c: New test.
--- gcc/regcprop.c.jj 2020-04-30 17:41:37.624675304 +0200
+++ gcc/regcprop.c 2021-05-05 16:24:01.667308941 +0200
@@ -382,10 +382,22 @@ copy_value (rtx dest, rtx src, struct va
(set (reg:HI R5) (reg:HI R[0-4]))
in which all registers have only 16 defined bits. */
- else if (partial_subreg_p (vd->e[sr].mode, GET_MODE (src))
- && partial_subreg_p (vd->e[sr].mode,
- vd->e[vd->e[sr].oldest_regno].mode))
- return;
+
+ /* If a narrower value is copied using wider mode, the upper bits
+ are undefined (could be e.g. a former paradoxical subreg). Signal
+ in that case we've only copied value using the narrower mode.
+ Consider:
+ (set (reg:DI r14) (mem:DI ...))
+ (set (reg:QI si) (reg:QI r14))
+ (set (reg:DI bp) (reg:DI r14))
+ (set (reg:DI r14) (const_int ...))
+ (set (reg:DI dx) (reg:DI si))
+ (set (reg:DI si) (const_int ...))
+ (set (reg:DI dx) (reg:DI bp))
+ The last set is not redundant, while the low 8 bits of dx are already
+ equal to low 8 bits of bp, the other bits are undefined. */
+ else if (partial_subreg_p (vd->e[sr].mode, GET_MODE (src)))
+ set_value_regno (dr, vd->e[sr].mode, vd);
/* Link DR at the end of the value chain used by SR. */
--- gcc/testsuite/gcc.target/i386/pr100342.c.jj 2021-05-05 17:01:29.139356719
+0200
+++ gcc/testsuite/gcc.target/i386/pr100342.c 2021-05-05 17:01:14.287521150
+0200
@@ -0,0 +1,70 @@
+/* PR rtl-optimization/100342 */
+/* { dg-do run { target int128 } } */
+/* { dg-options "-O2 -fno-dse -fno-forward-propagate -Wno-psabi -mno-sse2" } */
+
+#define SHL(x, y) ((x) << ((y) & (sizeof(x) * 8 - 1)))
+#define SHR(x, y) ((x) >> ((y) & (sizeof(x) * 8 - 1)))
+#define ROR(x, y) (SHR(x, y)) | (SHL(x, (sizeof(x) * 8 - (y))))
+#define SHLV(x, y) ((x) << ((y) & (sizeof((x)[0]) * 8 - 1)))
+#define SHLSV(x, y) ((x) << ((y) & (sizeof((y)[0]) * 8 - 1)))
+typedef unsigned char A;
+typedef unsigned char __attribute__((__vector_size__ (8))) B;
+typedef unsigned char __attribute__((__vector_size__ (16))) C;
+typedef unsigned char __attribute__((__vector_size__ (32))) D;
+typedef unsigned char __attribute__((__vector_size__ (64))) E;
+typedef unsigned short F;
+typedef unsigned short __attribute__((__vector_size__ (16))) G;
+typedef unsigned int H;
+typedef unsigned int __attribute__((__vector_size__ (32))) I;
+typedef unsigned long long J;
+typedef unsigned long long __attribute__((__vector_size__ (8))) K;
+typedef unsigned long long __attribute__((__vector_size__ (32))) L;
+typedef unsigned long long __attribute__((__vector_size__ (64))) M;
+typedef unsigned __int128 N;
+typedef unsigned __int128 __attribute__((__vector_size__ (16))) O;
+typedef unsigned __int128 __attribute__((__vector_size__ (32))) P;
+typedef unsigned __int128 __attribute__((__vector_size__ (64))) Q;
+B v1;
+D v2;
+L v3;
+K v4;
+I v5;
+O v6;
+
+B
+foo (A a, C b, E c, F d, G e, H f, J g, M h, N i, P j, Q k)
+{
+ b &= (A) f;
+ k += a;
+ G l = e;
+ D m = v2 >= (A) (J) v1;
+ J r = a + g;
+ L n = v3 <= f;
+ k -= i / f;
+ l -= (A) g;
+ c |= (A) d;
+ b -= (A) i;
+ J o = ROR (__builtin_clz (r), a);
+ K p = v4 | f, q = v4 <= f;
+ P s = SHLV (SHLSV (__builtin_bswap64 (i), (P) (0 < j)) <= 0, j);
+ n += a <= r;
+ M t = (M) (a / SHLV (c, 0)) != __builtin_bswap64 (i);
+ I u = f - v5;
+ E v = (E) h + (E) t + (E) k;
+ D w = (union { D b[2]; }) { }.b[0] + ((union { E b; }) v).b[1] + m + (D) u +
(D) n + (D) s;
+ C x = ((union { D b; }) w).b[1] + b + (C) l + (C) v6;
+ B y = ((union { C a; B b; }) x).b + ((union { C a; B b[2]; }) x).b[1] + (B)
p + (B) q;
+ J z = i + o;
+ F z2 = z;
+ A z3 = z2;
+ return y + z3;
+}
+
+int
+main ()
+{
+ B x = foo (0, (C) { }, (E) { }, 10, (G) { }, 4, 2, (M) { },
123842323652213865LL, (P) { 1 }, (Q) { });
+ if ((J) x != 0x2e2c2e2c2e2c2e30ULL)
+ __builtin_abort();
+ return 0;
+}
Jakub
