GCC mainline built for sh4-linux-gnu runs out of memory building a glibc test, which calls strncmp with very large constant size argument, resulting in the SH inline strncmp expansion trying to inline a fully unrolled expansion of strncmp for that size.
This patch limits that fully unrolled expansion to the case of less than 32 bytes. This is explicitly *not* trying to be optimal in any way (very likely a lower threshold makes sense), just to limit enough to avoid the out-of-memory issue in the glibc testsuite. I have *not* run the GCC testsuite for SH. I have verified that this allows the glibc testsuite to build OK, with both GCC mainline and GCC 7 branch (and that the included test builds quickly with patched GCC, runs out of memory with unpatched GCC). OK to commit (mainline and GCC 7 branch)? gcc: 2017-08-15 Joseph Myers <jos...@codesourcery.com> PR target/78460 * config/sh/sh-mem.cc (sh_expand_cmpnstr): Only unroll for constant count if that count is less than 32. gcc/testsuite: 2017-08-15 Joseph Myers <jos...@codesourcery.com> PR target/78460 * gcc.c-torture/compile/string-large-1.c: New test. Index: gcc/config/sh/sh-mem.cc =================================================================== --- gcc/config/sh/sh-mem.cc (revision 251105) +++ gcc/config/sh/sh-mem.cc (working copy) @@ -349,12 +349,13 @@ sh_expand_cmpnstr (rtx *operands) rtx len = copy_to_mode_reg (SImode, operands[3]); int constp = CONST_INT_P (operands[3]); + HOST_WIDE_INT bytes = constp ? INTVAL (operands[3]) : 0; const unsigned int addr1_alignment = MEM_ALIGN (operands[1]) / BITS_PER_UNIT; const unsigned int addr2_alignment = MEM_ALIGN (operands[2]) / BITS_PER_UNIT; /* Loop on a register count. */ - if (constp) + if (constp && bytes >= 0 && bytes < 32) { rtx tmp0 = gen_reg_rtx (SImode); rtx tmp3 = gen_reg_rtx (SImode); @@ -363,7 +364,6 @@ sh_expand_cmpnstr (rtx *operands) rtx_code_label *L_loop_long = gen_label_rtx (); rtx_code_label *L_end_loop_long = gen_label_rtx (); - int bytes = INTVAL (operands[3]); int witers = bytes / 4; if (witers > 1) Index: gcc/testsuite/gcc.c-torture/compile/string-large-1.c =================================================================== --- gcc/testsuite/gcc.c-torture/compile/string-large-1.c (nonexistent) +++ gcc/testsuite/gcc.c-torture/compile/string-large-1.c (working copy) @@ -0,0 +1,119 @@ +/* Test built-in string functions with large sizes. PR 78460. */ + +typedef __SIZE_TYPE__ size_t; + +#define SIZE1 ((size_t) -1) +#define SIZE2 (SIZE1 >> 1) +#define SIZE3 ((unsigned int) -1) +#define SIZE4 (SIZE3 >> 1) + +volatile int v1, v2, v3, v4; +void *volatile vp1, *volatile vp2, *volatile vp3, *volatile vp4; + +void +test_memchr (const void *a, int b) +{ + vp1 = __builtin_memchr (a, b, SIZE1); + vp2 = __builtin_memchr (a, b, SIZE2); + vp3 = __builtin_memchr (a, b, SIZE3); + vp4 = __builtin_memchr (a, b, SIZE4); +} + +void +test_memcmp (const void *a, const void *b) +{ + v1 = __builtin_memcmp (a, b, SIZE1); + v2 = __builtin_memcmp (a, b, SIZE2); + v3 = __builtin_memcmp (a, b, SIZE3); + v4 = __builtin_memcmp (a, b, SIZE4); +} + +void +test_memcpy (void *a, const void *b) +{ + vp1 = __builtin_memcpy (a, b, SIZE1); + vp2 = __builtin_memcpy (a, b, SIZE2); + vp3 = __builtin_memcpy (a, b, SIZE3); + vp4 = __builtin_memcpy (a, b, SIZE4); +} + +void +test_memmove (void *a, const void *b) +{ + vp1 = __builtin_memmove (a, b, SIZE1); + vp2 = __builtin_memmove (a, b, SIZE2); + vp3 = __builtin_memmove (a, b, SIZE3); + vp4 = __builtin_memmove (a, b, SIZE4); +} + +void +test_mempcpy (void *a, const void *b) +{ + vp1 = __builtin_mempcpy (a, b, SIZE1); + vp2 = __builtin_mempcpy (a, b, SIZE2); + vp3 = __builtin_mempcpy (a, b, SIZE3); + vp4 = __builtin_mempcpy (a, b, SIZE4); +} + +void +test_memset (void *a, int b) +{ + vp1 = __builtin_memset (a, b, SIZE1); + vp2 = __builtin_memset (a, b, SIZE2); + vp3 = __builtin_memset (a, b, SIZE3); + vp4 = __builtin_memset (a, b, SIZE4); +} + +void +test_stpncpy (char *a, const char *b) +{ + vp1 = __builtin_stpncpy (a, b, SIZE1); + vp2 = __builtin_stpncpy (a, b, SIZE2); + vp3 = __builtin_stpncpy (a, b, SIZE3); + vp4 = __builtin_stpncpy (a, b, SIZE4); +} + +void +test_strndup (const char *a) +{ + vp1 = __builtin_strndup (a, SIZE1); + vp2 = __builtin_strndup (a, SIZE2); + vp3 = __builtin_strndup (a, SIZE3); + vp4 = __builtin_strndup (a, SIZE4); +} + +void +test_strncasecmp (const char *a, const char *b) +{ + v1 = __builtin_strncasecmp (a, b, SIZE1); + v2 = __builtin_strncasecmp (a, b, SIZE2); + v3 = __builtin_strncasecmp (a, b, SIZE3); + v4 = __builtin_strncasecmp (a, b, SIZE4); +} + +void +test_strncat (char *a, const char *b) +{ + vp1 = __builtin_strncat (a, b, SIZE1); + vp2 = __builtin_strncat (a, b, SIZE2); + vp3 = __builtin_strncat (a, b, SIZE3); + vp4 = __builtin_strncat (a, b, SIZE4); +} + +void +test_strncmp (const char *a, const char *b) +{ + v1 = __builtin_strncmp (a, b, SIZE1); + v2 = __builtin_strncmp (a, b, SIZE2); + v3 = __builtin_strncmp (a, b, SIZE3); + v4 = __builtin_strncmp (a, b, SIZE4); +} + +void +test_strncpy (char *a, const char *b) +{ + vp1 = __builtin_strncpy (a, b, SIZE1); + vp2 = __builtin_strncpy (a, b, SIZE2); + vp3 = __builtin_strncpy (a, b, SIZE3); + vp4 = __builtin_strncpy (a, b, SIZE4); +} -- Joseph S. Myers jos...@codesourcery.com