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Re: [PATCH][AArch64] Improve bit-test-branch pattern to avoid unnecessary register clobber
- From: Jiong Wang <jiong dot wang at arm dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Cc: Richard Henderson <rth at redhat dot com>, Marcus Shawcroft <Marcus dot Shawcroft at arm dot com>
- Date: Mon, 19 Jan 2015 10:28:47 +0000
- Subject: Re: [PATCH][AArch64] Improve bit-test-branch pattern to avoid unnecessary register clobber
- Authentication-results: sourceware.org; auth=none
- References: <548EFFE8 dot 9040703 at arm dot com> <54B6F4BE dot 2000200 at redhat dot com>
On 14/01/15 22:59, Richard Henderson wrote:
On 12/15/2014 07:36 AM, Jiong Wang wrote:
+ char buf[64];
+ uint64_t val = ((uint64_t) 1) << UINTVAL (operands[1]);
+ sprintf (buf, "tst\t%%<w>0, %"PRId64, val);
+ output_asm_insn (buf, operands);
+ return "<bcond>\t%l2";
Better to simply modify the operand, as in
operands[1] = GEN_INT (HOST_WIDE_INT_1U << UINTVAL (operands[1]));
return "tst\t%<w>0, %1\;<bcond>\t%l2";
thanks, fixed.
ok for trunk ?
gcc/
2015-01-19 Ramana Radhakrishnanramana.radhakrishnan@arm.com
Jiong Wangjiong.wang@arm.com
* config/aarch64/aarch64.md (tb<optab><mode>1): Clobber CC reg instead of scratch reg.
(cb<optab><mode>1): Likewise.
* config/aarch64/iterators.md (bcond): New define_code_attr.
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 597ff8c..1e00396 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -466,13 +466,17 @@
(const_int 0))
(label_ref (match_operand 2 "" ""))
(pc)))
- (clobber (match_scratch:DI 3 "=r"))]
+ (clobber (reg:CC CC_REGNUM))]
""
- "*
- if (get_attr_length (insn) == 8)
- return \"ubfx\\t%<w>3, %<w>0, %1, #1\;<cbz>\\t%<w>3, %l2\";
- return \"<tbz>\\t%<w>0, %1, %l2\";
- "
+ {
+ if (get_attr_length (insn) == 8)
+ {
+ operands[1] = GEN_INT (HOST_WIDE_INT_1U << UINTVAL (operands[1]));
+ return "tst\t%<w>0, %1\;<bcond>\t%l2";
+ }
+ else
+ return "<tbz>\t%<w>0, %1, %l2";
+ }
[(set_attr "type" "branch")
(set (attr "length")
(if_then_else (and (ge (minus (match_dup 2) (pc)) (const_int -32768))
@@ -486,13 +490,21 @@
(const_int 0))
(label_ref (match_operand 1 "" ""))
(pc)))
- (clobber (match_scratch:DI 2 "=r"))]
+ (clobber (reg:CC CC_REGNUM))]
""
- "*
- if (get_attr_length (insn) == 8)
- return \"ubfx\\t%<w>2, %<w>0, <sizem1>, #1\;<cbz>\\t%<w>2, %l1\";
- return \"<tbz>\\t%<w>0, <sizem1>, %l1\";
- "
+ {
+ if (get_attr_length (insn) == 8)
+ {
+ char buf[64];
+ uint64_t val = ((uint64_t ) 1)
+ << (GET_MODE_SIZE (<MODE>mode) * BITS_PER_UNIT - 1);
+ sprintf (buf, "tst\t%%<w>0, %"PRId64, val);
+ output_asm_insn (buf, operands);
+ return "<bcond>\t%l1";
+ }
+ else
+ return "<tbz>\t%<w>0, <sizem1>, %l1";
+ }
[(set_attr "type" "branch")
(set (attr "length")
(if_then_else (and (ge (minus (match_dup 1) (pc)) (const_int -32768))
diff --git a/gcc/config/aarch64/iterators.md b/gcc/config/aarch64/iterators.md
index 7dd3917..bd144f9 100644
--- a/gcc/config/aarch64/iterators.md
+++ b/gcc/config/aarch64/iterators.md
@@ -823,6 +823,9 @@
(smax "s") (umax "u")
(smin "s") (umin "u")])
+;; Emit conditional branch instructions.
+(define_code_attr bcond [(eq "beq") (ne "bne") (lt "bne") (ge "beq")])
+
;; Emit cbz/cbnz depending on comparison type.
(define_code_attr cbz [(eq "cbz") (ne "cbnz") (lt "cbnz") (ge "cbz")])
diff --git a/gcc/testsuite/gcc.target/aarch64/long_range_bit_test_branch_1.c b/gcc/testsuite/gcc.target/aarch64/long_range_bit_test_branch_1.c
new file mode 100644
index 0000000..d4782e9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/long_range_bit_test_branch_1.c
@@ -0,0 +1,166 @@
+int dec (int);
+
+#define CASE_ENTRY(n) \
+ case n: \
+ sum = a / n; \
+ sum = sum * (n - 1); \
+ sum = dec (sum); \
+ sum = sum / (n + 1); \
+ sum = dec (sum); \
+ sum = sum / (n + 2); \
+ sum = dec (sum); \
+ sum = sum / (n + 3); \
+ sum = dec (sum); \
+ sum = sum / (n + 4); \
+ sum = dec (sum); \
+ sum = sum / (n + 5); \
+ sum = dec (sum); \
+ sum = sum / (n + 6); \
+ sum = dec (sum); \
+ sum = sum / (n + 7); \
+ sum = dec (sum); \
+ sum = sum / (n + 8); \
+ sum = dec (sum); \
+ sum = sum / (n + 9); \
+ sum = dec (sum); \
+ sum = sum / (n + 10); \
+ sum = dec (sum); \
+ sum = sum / (n + 11); \
+ sum = dec (sum); \
+ sum = sum / (n + 12); \
+ sum = dec (sum); \
+ sum = sum / (n + 13); \
+ sum = dec (sum); \
+ sum = sum / (n + 14); \
+ sum = dec (sum); \
+ sum = sum / (n + 15); \
+ sum = dec (sum); \
+ sum = sum / (n + 16); \
+ sum = dec (sum); \
+ sum = sum / (n + 17); \
+ sum = dec (sum); \
+ sum = sum / (n + 18); \
+ sum = dec (sum); \
+ sum = sum / (n + 19); \
+ sum = dec (sum); \
+ sum = sum / (n + 20); \
+ sum = dec (sum); \
+ sum = sum / (n + 21); \
+ sum = dec (sum); \
+ sum = sum / (n + 22); \
+ sum = dec (sum); \
+ sum = sum / (n + 23); \
+ sum = dec (sum); \
+ sum = sum / (n + 24); \
+ sum = dec (sum); \
+ sum = sum / (n + 25); \
+ sum = dec (sum); \
+ sum = sum / (n + 26); \
+ sum = dec (sum); \
+ sum = sum / (n + 27); \
+ sum = dec (sum); \
+ sum = sum / (n + 28); \
+ sum = dec (sum); \
+ sum = sum / (n + 29); \
+ sum = dec (sum); \
+ sum = sum / (n + 30); \
+ sum = dec (sum); \
+ sum = sum / (n + 31); \
+ break;
+
+int
+cbranch (int a, int b, int c, int d, long long addend)
+{
+ long long sum;
+ if (a & 0x2)
+ {
+start:
+ sum = b * c;
+ sum = sum + b + c;
+#ifdef CB
+ if (sum < 0)
+ goto start;
+#endif
+ }
+ else
+ {
+ switch (a/d)
+ {
+ CASE_ENTRY (1)
+ CASE_ENTRY (2)
+ CASE_ENTRY (3)
+ CASE_ENTRY (4)
+ CASE_ENTRY (5)
+ CASE_ENTRY (6)
+ CASE_ENTRY (7)
+ CASE_ENTRY (8)
+ CASE_ENTRY (9)
+ CASE_ENTRY (10)
+ CASE_ENTRY (11)
+ CASE_ENTRY (12)
+ CASE_ENTRY (13)
+ CASE_ENTRY (14)
+ CASE_ENTRY (15)
+ CASE_ENTRY (16)
+ CASE_ENTRY (17)
+ CASE_ENTRY (18)
+ CASE_ENTRY (19)
+ CASE_ENTRY (20)
+ CASE_ENTRY (21)
+ CASE_ENTRY (22)
+ CASE_ENTRY (23)
+ CASE_ENTRY (24)
+ CASE_ENTRY (25)
+ CASE_ENTRY (26)
+ CASE_ENTRY (27)
+ CASE_ENTRY (28)
+ CASE_ENTRY (29)
+ CASE_ENTRY (30)
+ CASE_ENTRY (31)
+ CASE_ENTRY (32)
+ CASE_ENTRY (33)
+ CASE_ENTRY (34)
+ CASE_ENTRY (35)
+ CASE_ENTRY (36)
+ CASE_ENTRY (37)
+ CASE_ENTRY (38)
+ CASE_ENTRY (39)
+ CASE_ENTRY (40)
+ CASE_ENTRY (41)
+ CASE_ENTRY (42)
+ CASE_ENTRY (43)
+ CASE_ENTRY (44)
+ CASE_ENTRY (45)
+ CASE_ENTRY (46)
+ CASE_ENTRY (47)
+ CASE_ENTRY (48)
+ CASE_ENTRY (49)
+ CASE_ENTRY (50)
+ CASE_ENTRY (51)
+ CASE_ENTRY (52)
+ CASE_ENTRY (53)
+ CASE_ENTRY (54)
+ CASE_ENTRY (55)
+ CASE_ENTRY (56)
+ CASE_ENTRY (57)
+ CASE_ENTRY (58)
+ CASE_ENTRY (59)
+ CASE_ENTRY (60)
+ CASE_ENTRY (61)
+ CASE_ENTRY (62)
+ CASE_ENTRY (63)
+ CASE_ENTRY (64)
+ }
+
+#ifdef CB
+ if (sum < 0)
+ goto start;
+#else
+
+ if (sum & 0x2000000000)
+ goto start;
+#endif
+ }
+
+ return sum;
+}