From af039edf70b26a0033a9f66338da2faebc6c5027 Mon Sep 17 00:00:00 2001 From: Philipp Tomsich Date: Fri, 1 Apr 2022 14:42:58 +0200 Subject: [PATCH] RISC-V: Implement C[LT]Z_DEFINED_VALUE_AT_ZERO The Zbb support has introduced ctz and clz to the backend, but some transformations in GCC need to know what the value of c[lt]z at zero is. This affects how the optab is generated and may suppress use of CLZ/CTZ in tree passes. Among other things, this is needed for the transformation of table-based ctz-implementations, such as in deepsjeng, to work (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90838). Prior to this change, the test case from PR90838 would compile to on RISC-V targets with Zbb: myctz: lui a4,%hi(.LC0) ld a4,%lo(.LC0)(a4) neg a5,a0 and a5,a5,a0 mul a5,a5,a4 lui a4,%hi(.LANCHOR0) addi a4,a4,%lo(.LANCHOR0) srli a5,a5,58 sh2add a5,a5,a4 lw a0,0(a5) ret After this change, we get: myctz: ctz a0,a0 andi a0,a0,63 ret Testing this with deepsjeng_r (from SPEC 2017) against QEMU, this shows a clear reduction in dynamic instruction count: - before 1961888067076 - after 1907928279874 (2.75% reduction) This also merges the various target-specific test-cases (for x86-64, aarch64 and riscv) within gcc.dg/pr90838.c. This extends the macros (i.e., effective-target keywords) used in testing (lib/target-supports.exp) to reliably distinguish between RV32 and RV64 via __riscv_xlen (i.e., the integer register bitwidth) : testing for ILP32 could be misleading (as ILP32 is a valid memory model for 64bit systems). gcc/ChangeLog: * config/riscv/riscv.h (CLZ_DEFINED_VALUE_AT_ZERO): Implement. (CTZ_DEFINED_VALUE_AT_ZERO): Same. * doc/sourcebuild.texi: add documentation for RISC-V specific test target keywords gcc/testsuite/ChangeLog: * gcc.dg/pr90838.c: Add additional flags (dg-additional-options) when compiling for riscv64 and subsume gcc.target/aarch64/pr90838.c and gcc.target/i386/pr95863-2.c. * gcc.target/aarch64/pr90838.c: Removed. * gcc.target/i386/pr95863-2.c: Removed. * lib/target-supports.exp: Recognize RV32 or RV64 via XLEN Signed-off-by: Philipp Tomsich Signed-off-by: Manolis Tsamis Co-authored-by: Manolis Tsamis (cherry picked from commit 16f7fcadac19dabd04a5abbe6601df52d22e9685) --- gcc/config/riscv/riscv.h | 5 +++ gcc/doc/sourcebuild.texi | 12 ++++++ gcc/testsuite/gcc.dg/pr90838.c | 25 ++++++++++++ gcc/testsuite/gcc.target/aarch64/pr90838.c | 64 ------------------------------ gcc/testsuite/gcc.target/i386/pr95863-2.c | 27 ------------- gcc/testsuite/lib/target-supports.exp | 30 ++++++++++++++ 6 files changed, 72 insertions(+), 91 deletions(-) delete mode 100644 gcc/testsuite/gcc.target/aarch64/pr90838.c delete mode 100644 gcc/testsuite/gcc.target/i386/pr95863-2.c diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h index 8a4d2cf..b191606 100644 --- a/gcc/config/riscv/riscv.h +++ b/gcc/config/riscv/riscv.h @@ -1004,4 +1004,9 @@ extern void riscv_remove_unneeded_save_restore_calls (void); #define HARD_REGNO_RENAME_OK(FROM, TO) riscv_hard_regno_rename_ok (FROM, TO) +#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \ + ((VALUE) = GET_MODE_UNIT_BITSIZE (MODE), 2) +#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \ + ((VALUE) = GET_MODE_UNIT_BITSIZE (MODE), 2) + #endif /* ! GCC_RISCV_H */ diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi index 613ac29..71c0484 100644 --- a/gcc/doc/sourcebuild.texi +++ b/gcc/doc/sourcebuild.texi @@ -2420,6 +2420,18 @@ PowerPC target pre-defines macro _ARCH_PWR9 which means the @code{-mcpu} setting is Power9 or later. @end table +@subsection RISC-V specific attributes + +@table @code + +@item rv32 +Test system has an integer register width of 32 bits. + +@item rv64 +Test system has an integer register width of 64 bits. + +@end table + @subsubsection Other hardware attributes @c Please keep this table sorted alphabetically. diff --git a/gcc/testsuite/gcc.dg/pr90838.c b/gcc/testsuite/gcc.dg/pr90838.c index 41c5dab..7502b84 100644 --- a/gcc/testsuite/gcc.dg/pr90838.c +++ b/gcc/testsuite/gcc.dg/pr90838.c @@ -1,5 +1,8 @@ /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-forwprop2-details" } */ +/* { dg-additional-options "-mbmi" { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } */ +/* { dg-additional-options "-march=rv64gc_zbb" { target { rv64 } } } */ +/* { dg-additional-options "-march=rv32gc_zbb" { target { rv32 } } } */ int ctz1 (unsigned x) { @@ -56,4 +59,26 @@ int ctz4 (unsigned long x) return table[(lsb * magic) >> 58]; } +/* { dg-final { scan-tree-dump-times {= \.CTZ} 4 "forwprop2" { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-times "tzcntq\t" 1 { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-times "tzcntl\t" 3 { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-times "andl\t" 2 { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-not "negq" { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-not "imulq" { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ +/* { dg-final { scan-assembler-not "shrq" { target { { i?86-*-* x86_64-*-* } && { ! { ia32 } } } } } } */ + /* { dg-final { scan-tree-dump-times {= \.CTZ} 4 "forwprop2" { target aarch64*-*-* } } } */ +/* { dg-final { scan-assembler-times "clz\t" 4 { target aarch64*-*-* } } } */ +/* { dg-final { scan-assembler-times "and\t" 2 { target aarch64*-*-* } } } */ +/* { dg-final { scan-assembler-not "cmp\t.*0" { target aarch64*-*-* } } } */ + +/* { dg-final { scan-tree-dump-times {= \.CTZ} 4 "forwprop2" { target { rv64 } } } } */ +/* { dg-final { scan-assembler-times "ctz\t" 1 { target { rv64 } } } } */ +/* { dg-final { scan-assembler-times "ctzw\t" 3 { target { rv64 } } } } */ +/* { dg-final { scan-assembler-times "andi\t" 2 { target { rv64 } } } } */ +/* { dg-final { scan-assembler-not "mul" { target { rv64 } } } } */ + +/* { dg-final { scan-tree-dump-times {= \.CTZ} 3 "forwprop2" { target { rv32 } } } } */ +/* { dg-final { scan-assembler-times "ctz\t" 3 { target { rv32 } } } } */ +/* { dg-final { scan-assembler-times "andi\t" 1 { target { rv32 } } } } */ +/* { dg-final { scan-assembler-times "mul\t" 1 { target { rv32 } } } } */ diff --git a/gcc/testsuite/gcc.target/aarch64/pr90838.c b/gcc/testsuite/gcc.target/aarch64/pr90838.c deleted file mode 100644 index e1e19ac..0000000 --- a/gcc/testsuite/gcc.target/aarch64/pr90838.c +++ /dev/null @@ -1,64 +0,0 @@ -/* { dg-do compile } */ -/* { dg-options "-O2" } */ - -int ctz1 (unsigned x) -{ - static const char table[32] = - { - 0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8, - 31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9 - }; - - return table[((unsigned)((x & -x) * 0x077CB531U)) >> 27]; -} - -int ctz2 (unsigned x) -{ -#define u 0 - static short table[64] = - { - 32, 0, 1,12, 2, 6, u,13, 3, u, 7, u, u, u, u,14, - 10, 4, u, u, 8, u, u,25, u, u, u, u, u,21,27,15, - 31,11, 5, u, u, u, u, u, 9, u, u,24, u, u,20,26, - 30, u, u, u, u,23, u,19,29, u,22,18,28,17,16, u - }; - - x = (x & -x) * 0x0450FBAF; - return table[x >> 26]; -} - -int ctz3 (unsigned x) -{ - static int table[32] = - { - 0, 1, 2,24, 3,19, 6,25, 22, 4,20,10,16, 7,12,26, - 31,23,18, 5,21, 9,15,11,30,17, 8,14,29,13,28,27 - }; - - if (x == 0) return 32; - x = (x & -x) * 0x04D7651F; - return table[x >> 27]; -} - -static const unsigned long long magic = 0x03f08c5392f756cdULL; - -static const char table[64] = { - 0, 1, 12, 2, 13, 22, 17, 3, - 14, 33, 23, 36, 18, 58, 28, 4, - 62, 15, 34, 26, 24, 48, 50, 37, - 19, 55, 59, 52, 29, 44, 39, 5, - 63, 11, 21, 16, 32, 35, 57, 27, - 61, 25, 47, 49, 54, 51, 43, 38, - 10, 20, 31, 56, 60, 46, 53, 42, - 9, 30, 45, 41, 8, 40, 7, 6, -}; - -int ctz4 (unsigned long x) -{ - unsigned long lsb = x & -x; - return table[(lsb * magic) >> 58]; -} - -/* { dg-final { scan-assembler-times "clz\t" 4 } } */ -/* { dg-final { scan-assembler-times "and\t" 2 } } */ -/* { dg-final { scan-assembler-not "cmp\t.*0" } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr95863-2.c b/gcc/testsuite/gcc.target/i386/pr95863-2.c deleted file mode 100644 index cb56dfc..0000000 --- a/gcc/testsuite/gcc.target/i386/pr95863-2.c +++ /dev/null @@ -1,27 +0,0 @@ -/* { dg-do compile { target { ! ia32 } } } */ -/* { dg-options "-O -mbmi" } */ - -static const unsigned long long magic = 0x03f08c5392f756cdULL; - -static const char table[64] = { - 0, 1, 12, 2, 13, 22, 17, 3, - 14, 33, 23, 36, 18, 58, 28, 4, - 62, 15, 34, 26, 24, 48, 50, 37, - 19, 55, 59, 52, 29, 44, 39, 5, - 63, 11, 21, 16, 32, 35, 57, 27, - 61, 25, 47, 49, 54, 51, 43, 38, - 10, 20, 31, 56, 60, 46, 53, 42, - 9, 30, 45, 41, 8, 40, 7, 6, -}; - -int ctz4 (unsigned long long x) -{ - unsigned long long lsb = x & -x; - return table[(lsb * magic) >> 58]; -} - -/* { dg-final { scan-assembler-times "tzcntq\t" 1 } } */ -/* { dg-final { scan-assembler-times "andl\t" 1 } } */ -/* { dg-final { scan-assembler-not "negq" } } */ -/* { dg-final { scan-assembler-not "imulq" } } */ -/* { dg-final { scan-assembler-not "shrq" } } */ diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp index 2d5d053..244fe23 100644 --- a/gcc/testsuite/lib/target-supports.exp +++ b/gcc/testsuite/lib/target-supports.exp @@ -1689,6 +1689,36 @@ proc check_linker_plugin_available { } { } "-flto -fuse-linker-plugin"] } +# Return 1 if the target is RV32, 0 otherwise. Cache the result. + +proc check_effective_target_rv32 { } { + # Check that we are compiling for RV32 by checking the xlen size. + return [check_no_compiler_messages riscv_rv32 assembly { + #if !defined(__riscv_xlen) + #error "__riscv_xlen not defined!" + #else + #if __riscv_xlen != 32 + #error "Not RV32" + #endif + #endif + }] +} + +# Return 1 if the target is RV64, 0 otherwise. Cache the result. + +proc check_effective_target_rv64 { } { + # Check that we are compiling for RV64 by checking the xlen size. + return [check_no_compiler_messages riscv_rv64 assembly { + #if !defined(__riscv_xlen) + #error "__riscv_xlen not defined!" + #else + #if __riscv_xlen != 64 + #error "Not RV64" + #endif + #endif + }] +} + # Return 1 if the target OS supports running SSE executables, 0 # otherwise. Cache the result. -- 2.7.4