https://gcc.gnu.org/g:e232dc3bb5c3e8f8a3749239135b7b859a204fc7
commit r15-5116-ge232dc3bb5c3e8f8a3749239135b7b859a204fc7
Author: Soumya AR <soum...@nvidia.com>
Date: Tue Nov 12 09:26:24 2024 +0530
Match: Optimize log (x) CMP CST and exp (x) CMP CST operations
This patch implements transformations for the following optimizations.
logN(x) CMP CST -> x CMP expN(CST)
expN(x) CMP CST -> x CMP logN(CST)
Where CMP expands to ge and le operations.
For example:
int
foo (float x)
{
return __builtin_logf (x) <= 0.0f;
}
can just be:
int
foo (float x)
{
return x <= 1.0f;
}
The patch was bootstrapped and regtested on aarch64-linux-gnu, no
regression.
OK for mainline?
Signed-off-by: Soumya AR <soum...@nvidia.com>
gcc/ChangeLog:
* match.pd: Fold logN(x) CMP CST -> x CMP expN(CST)
and expN(x) CMP CST -> x CMP logN(CST)
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/log_exp.c: New test.
Diff:
---
gcc/match.pd | 15 ++++++++++++-
gcc/testsuite/gcc.dg/tree-ssa/log_exp.c | 40 +++++++++++++++++++++++++++++++++
2 files changed, 54 insertions(+), 1 deletion(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index 00988241348a..fc33b9ac3b1b 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -8347,7 +8347,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Simplify logN(a)-logN(b) into logN(a/b). */
(simplify
(minus (logs:s @0) (logs:s @1))
- (logs (rdiv @0 @1)))))
+ (logs (rdiv @0 @1))))
+
+ (for cmp (le ge)
+ (for logs (LOG LOG2 LOG10)
+ exps (EXP EXP2 EXP10)
+ /* Simplify logN (x) CMP CST into x CMP expN (CST) */
+ (simplify
+ (cmp:c (logs:s @0) REAL_CST@1)
+ (cmp @0 (exps @1)))
+
+ /* Simplify expN (x) CMP CST into x CMP logN (CST) */
+ (simplify
+ (cmp:c (exps:s @0) REAL_CST@1)
+ (cmp @0 (logs @1))))))
(for logs (LOG LOG2 LOG10 LOG10)
exps (EXP EXP2 EXP10 POW10)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/log_exp.c
b/gcc/testsuite/gcc.dg/tree-ssa/log_exp.c
new file mode 100644
index 000000000000..1c5d967cdf76
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/log_exp.c
@@ -0,0 +1,40 @@
+/* { dg-do link } */
+/* { dg-options "-O2 -ffast-math" } */
+/* { dg-require-effective-target c99_runtime } */
+
+#include <stdbool.h>
+
+extern void link_error(void);
+
+#define T(FUNC1, FUNC2, CMP, TYPE, C_TY, ID) \
+void test_##FUNC1##_##FUNC2##_##ID (TYPE x) \
+{ \
+ TYPE a = 10.0##C_TY; \
+ TYPE t1 = __builtin_##FUNC1(x); \
+ bool b1 = t1 CMP a; \
+ TYPE t2 = __builtin_##FUNC2(a); \
+ bool b2 = x CMP t2; \
+ if (b1 != b2) \
+ link_error(); \
+}
+
+#define TEST(FUNC1, FUNC2, TYPE, C_TY) \
+ T(FUNC1, FUNC2, <=, TYPE, C_TY, 1) \
+ T(FUNC1, FUNC2, >=, TYPE, C_TY, 2) \
+
+#define TEST_ALL(TYPE, C_TY, F_TY) \
+ TEST(exp##F_TY, log##F_TY, TYPE, C_TY) \
+ TEST(exp2##F_TY, log2##F_TY, TYPE, C_TY) \
+ TEST(exp10##F_TY, log10##F_TY, TYPE, C_TY) \
+ TEST(log##F_TY, exp##F_TY, TYPE, C_TY) \
+ TEST(log2##F_TY, exp2##F_TY, TYPE, C_TY) \
+ TEST(log10##F_TY, exp10##F_TY, TYPE, C_TY)
+
+TEST_ALL(double, , )
+TEST_ALL(float, f, f)
+TEST_ALL(long double, L, l)
+
+int main (void)
+{
+ return 0;
+}
