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In http://gcc.gnu.org/ml/gcc-patches/2009-06/msg02044.html, Richard
Guenther approved a version of this patch for trunk and the branches.
The mainline patch works for the 4.4 branch but not 4.3, where there
are additional passes that do constant folding. This patch disables
RTL constant folding for binary operations involving decimal float
constants.
Bootstrapped and regression tested on powerpc64-linux, -m32/-m64; OK
for the 4.3 branch?
2009-07-15 Janis Johnson <janis187@xxxxxxxxxx>
gcc/
PR c/39902
* tree.c (real_zerop, real_onep, real_twop, real_minus_onep):
Special-case decimal float constants.
* simplify-rtx.c (simplify_binary_operation): Skip for decimal float.
gcc/testsuite/
PR c/39902
* gcc.dg/dfp/pr39902.c: New test.
Index: gcc/tree.c
===================================================================
--- gcc/tree.c (revision 148982)
+++ gcc/tree.c (working copy)
@@ -1543,7 +1543,8 @@ tree_floor_log2 (const_tree expr)
: floor_log2 (low));
}
-/* Return 1 if EXPR is the real constant zero. */
+/* Return 1 if EXPR is the real constant zero. Trailing zeroes matter for
+ decimal float constants, so don't return 1 for them. */
int
real_zerop (const_tree expr)
@@ -1551,13 +1552,16 @@ real_zerop (const_tree expr)
STRIP_NOPS (expr);
return ((TREE_CODE (expr) == REAL_CST
- && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst0))
+ && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst0)
+ && !(DECIMAL_FLOAT_MODE_P (TYPE_MODE (TREE_TYPE (expr)))))
|| (TREE_CODE (expr) == COMPLEX_CST
&& real_zerop (TREE_REALPART (expr))
&& real_zerop (TREE_IMAGPART (expr))));
}
-/* Return 1 if EXPR is the real constant one in real or complex form. */
+/* Return 1 if EXPR is the real constant one in real or complex form.
+ Trailing zeroes matter for decimal float constants, so don't return
+ 1 for them. */
int
real_onep (const_tree expr)
@@ -1565,13 +1569,15 @@ real_onep (const_tree expr)
STRIP_NOPS (expr);
return ((TREE_CODE (expr) == REAL_CST
- && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst1))
+ && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst1)
+ && !(DECIMAL_FLOAT_MODE_P (TYPE_MODE (TREE_TYPE (expr)))))
|| (TREE_CODE (expr) == COMPLEX_CST
&& real_onep (TREE_REALPART (expr))
&& real_zerop (TREE_IMAGPART (expr))));
}
-/* Return 1 if EXPR is the real constant two. */
+/* Return 1 if EXPR is the real constant two. Trailing zeroes matter
+ for decimal float constants, so don't return 1 for them. */
int
real_twop (const_tree expr)
@@ -1579,13 +1585,15 @@ real_twop (const_tree expr)
STRIP_NOPS (expr);
return ((TREE_CODE (expr) == REAL_CST
- && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst2))
+ && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconst2)
+ && !(DECIMAL_FLOAT_MODE_P (TYPE_MODE (TREE_TYPE (expr)))))
|| (TREE_CODE (expr) == COMPLEX_CST
&& real_twop (TREE_REALPART (expr))
&& real_zerop (TREE_IMAGPART (expr))));
}
-/* Return 1 if EXPR is the real constant minus one. */
+/* Return 1 if EXPR is the real constant minus one. Trailing zeroes
+ matter for decimal float constants, so don't return 1 for them. */
int
real_minus_onep (const_tree expr)
@@ -1593,7 +1601,8 @@ real_minus_onep (const_tree expr)
STRIP_NOPS (expr);
return ((TREE_CODE (expr) == REAL_CST
- && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconstm1))
+ && REAL_VALUES_EQUAL (TREE_REAL_CST (expr), dconstm1)
+ && !(DECIMAL_FLOAT_MODE_P (TYPE_MODE (TREE_TYPE (expr)))))
|| (TREE_CODE (expr) == COMPLEX_CST
&& real_minus_onep (TREE_REALPART (expr))
&& real_zerop (TREE_IMAGPART (expr))));
Index: gcc/simplify-rtx.c
===================================================================
--- gcc/simplify-rtx.c (revision 148982)
+++ gcc/simplify-rtx.c (working copy)
@@ -1533,6 +1533,11 @@ simplify_binary_operation (enum rtx_code
gcc_assert (GET_RTX_CLASS (code) != RTX_COMPARE);
gcc_assert (GET_RTX_CLASS (code) != RTX_COMM_COMPARE);
+ /* Do not simplify decimal floating-point operations, for which trailing
+ zeroes in constants are significant. */
+ if (DECIMAL_FLOAT_MODE_P (mode))
+ return NULL;
+
/* Make sure the constant is second. */
if (GET_RTX_CLASS (code) == RTX_COMM_ARITH
&& swap_commutative_operands_p (op0, op1))
Index: gcc/testsuite/gcc.dg/dfp/pr39902.c
===================================================================
--- gcc/testsuite/gcc.dg/dfp/pr39902.c (revision 0)
+++ gcc/testsuite/gcc.dg/dfp/pr39902.c (revision 0)
@@ -0,0 +1,239 @@
+/* { dg-options "--std=gnu99" } */
+
+/* Check that optimizations like (x * 1) to x, or (x * -1) to -x,
+ do not apply to decimal float computations where trailing zeroes
+ are significant. */
+
+extern void abort (void);
+int failcnt;
+
+#ifdef DBG
+extern int printf (const char *, ...);
+#define FAILURE { printf ("failed at line %d\n", __LINE__); failcnt++; }
+#else
+#define FAILURE abort ();
+#endif
+
+#define COMPARE32(A,B) \
+ A.i == B.i
+
+#define COMPARE64(A,B) \
+ A.i[0] == B.i[0] && A.i[1] == B.i[1]
+
+#define COMPARE128(A,B) \
+ A.i[0] == B.i[0] && A.i[1] == B.i[1] && A.i[2] == B.i[2] && A.i[3] == B.i[3]
+
+typedef union {
+ _Decimal32 d;
+ unsigned int i;
+} u32;
+
+typedef union {
+ _Decimal64 d;
+ unsigned int i[2];
+} u64;
+
+typedef union {
+ _Decimal128 d;
+ unsigned int i[4];
+} u128;
+
+volatile u32 p32_1;
+volatile u32 p32_1_0;
+volatile u32 p32_2_0;
+volatile u32 m32_1;
+volatile u32 m32_1_0;
+volatile u32 m32_2_0;
+volatile u32 a32;
+
+volatile u64 p64_1;
+volatile u64 p64_1_0;
+volatile u64 p64_2_0;
+volatile u64 m64_1;
+volatile u64 m64_1_0;
+volatile u64 m64_2_0;
+volatile u64 a64;
+
+volatile u128 p128_1;
+volatile u128 p128_1_0;
+volatile u128 p128_2_0;
+volatile u128 m128_1;
+volatile u128 m128_1_0;
+volatile u128 m128_2_0;
+volatile u128 a128;
+
+void
+init32 (void)
+{
+ p32_1.d = 1.DF;
+ p32_1_0.d = 1.0DF;
+ p32_2_0.d = 2.0DF;
+ m32_1.d = -1.DF;
+ m32_1_0.d = -1.0DF;
+ m32_2_0.d = -2.0DF;
+}
+
+void
+init64 (void)
+{
+ p64_1.d = 1.DD;
+ p64_1_0.d = 1.0DD;
+ p64_2_0.d = 2.0DD;
+ m64_1.d = -1.DD;
+ m64_1_0.d = -1.0DD;
+ m64_2_0.d = -2.0DD;
+}
+
+void
+init128 (void)
+{
+ p128_1.d = 1.DL;
+ p128_1_0.d = 1.0DL;
+ p128_2_0.d = 2.0DL;
+ m128_1.d = -1.DL;
+ m128_1_0.d = -1.0DL;
+ m128_2_0.d = -2.0DL;
+}
+
+void
+doit32 (void)
+{
+ /* Multiplying by a value with no trailing zero should not change the
+ quantum exponent. */
+
+ a32.d = p32_2_0.d * p32_1.d;
+ if (! (COMPARE32 (a32, p32_2_0)))
+ FAILURE
+
+ a32.d = p32_2_0.d * 1.DF;
+ if (! (COMPARE32 (a32, p32_2_0)))
+ FAILURE
+
+ a32.d = p32_2_0.d * m32_1.d;
+ if (! (COMPARE32 (a32, m32_2_0)))
+ FAILURE
+
+ a32.d = p32_2_0.d * -1.DF;
+ if (! (COMPARE32 (a32, m32_2_0)))
+ FAILURE
+
+ /* Multiplying by a value with a trailing zero should change the
+ quantum exponent. */
+
+ a32.d = p32_2_0.d * p32_1_0.d;
+ if (COMPARE32 (a32, p32_2_0))
+ FAILURE
+
+ a32.d = p32_2_0.d * 1.0DF;
+ if (COMPARE32 (a32, p32_2_0))
+ FAILURE
+
+ a32.d = p32_2_0.d * m32_1_0.d;
+ if (COMPARE32 (a32, m32_2_0))
+ FAILURE
+
+ a32.d = p32_2_0.d * -1.0DF;
+ if (COMPARE32 (a32, m32_2_0))
+ FAILURE
+}
+
+void
+doit64 (void)
+{
+ /* Multiplying by a value with no trailing zero should not change the
+ quantum exponent. */
+
+ a64.d = p64_2_0.d * p64_1.d;
+ if (! (COMPARE64 (a64, p64_2_0)))
+ FAILURE
+
+ a64.d = p64_2_0.d * 1.DD;
+ if (! (COMPARE64 (a64, p64_2_0)))
+ FAILURE
+
+ a64.d = p64_2_0.d * m64_1.d;
+ if (! (COMPARE64 (a64, m64_2_0)))
+ FAILURE
+
+ a64.d = p64_2_0.d * -1.DD;
+ if (! (COMPARE64 (a64, m64_2_0)))
+ FAILURE
+
+ /* Multiplying by a value with a trailing zero should change the
+ quantum exponent. */
+
+ a64.d = p64_2_0.d * p64_1_0.d;
+ if (COMPARE64 (a64, p64_2_0))
+ FAILURE
+
+ a64.d = p64_2_0.d * 1.0DD;
+ if (COMPARE64 (a64, p64_2_0))
+ FAILURE
+
+ a64.d = p64_2_0.d * m64_1_0.d;
+ if (COMPARE64 (a64, m64_2_0))
+ FAILURE
+
+ a64.d = p64_2_0.d * -1.0DD;
+ if (COMPARE64 (a64, m64_2_0))
+ FAILURE
+}
+
+void
+doit128 (void)
+{
+ /* Multiplying by a value with no trailing zero should not change the
+ quantum exponent. */
+
+ a128.d = p128_2_0.d * p128_1_0.d;
+ if (COMPARE128 (a128, p128_2_0))
+ FAILURE
+
+ a128.d = p128_2_0.d * 1.0DD;
+ if (COMPARE128 (a128, p128_2_0))
+ FAILURE
+
+ a128.d = p128_2_0.d * m128_1_0.d;
+ if (COMPARE128 (a128, m128_2_0))
+ FAILURE
+
+ a128.d = p128_2_0.d * -1.0DD;
+ if (COMPARE128 (a128, m128_2_0))
+ FAILURE
+
+ /* Multiplying by a value with a trailing zero should change the
+ quantum exponent. */
+
+ a128.d = p128_2_0.d * p128_1.d;
+ if (! (COMPARE128 (a128, p128_2_0)))
+ FAILURE
+
+ a128.d = p128_2_0.d * 1.DD;
+ if (! (COMPARE128 (a128, p128_2_0)))
+ FAILURE
+
+ a128.d = p128_2_0.d * m128_1.d;
+ if (! (COMPARE128 (a128, m128_2_0)))
+ FAILURE
+
+ a128.d = p128_2_0.d * -1.DD;
+ if (! (COMPARE128 (a128, m128_2_0)))
+ FAILURE
+}
+
+int
+main (void)
+{
+ init32 ();
+ init64 ();
+ init128 ();
+
+ doit32 ();
+ doit64 ();
+ doit128 ();
+
+ if (failcnt != 0)
+ abort ();
+
+ return 0;
+}
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