lower-bitint: Avoid nested casts in muldiv/float operands [PR112941]

Multiplication/division/modulo/float operands are handled by libgcc calls
and so need to be passed as array of limbs with precision argument,
using handle_operand_addr.  That code can't deal with more than one cast,
so the following patch avoids merging those cases.
.MUL_OVERFLOW calls use the same code, but we don't actually try to merge
the operands in that case already.

2023-12-21  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/112941
	* gimple-lower-bitint.cc (gimple_lower_bitint): Disallow merging
	a cast with multiplication, division or conversion to floating point
	if rhs1 of the cast is result of another single use cast in the same
	bb.

	* gcc.dg/bitint-56.c: New test.
	* gcc.dg/bitint-57.c: New test.

diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index 8b392b17a046bc0bb0ab2ce7387c47e89e39476f..045836ece22fa43a6d5e1eb5dbab60e78d2ae533 100644 (file)
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -6060,6 +6060,26 @@ gimple_lower_bitint (void)
                          || (bitint_precision_kind (TREE_TYPE (rhs1))
                              < bitint_prec_large))
                        continue;
+                     if (is_gimple_assign (use_stmt))
+                       switch (gimple_assign_rhs_code (use_stmt))
+                         {
+                         case MULT_EXPR:
+                         case TRUNC_DIV_EXPR:
+                         case TRUNC_MOD_EXPR:
+                         case FLOAT_EXPR:
+                           /* Uses which use handle_operand_addr can't
+                              deal with nested casts.  */
+                           if (TREE_CODE (rhs1) == SSA_NAME
+                               && gimple_assign_cast_p
+                                    (SSA_NAME_DEF_STMT (rhs1))
+                               && has_single_use (rhs1)
+                               && (gimple_bb (SSA_NAME_DEF_STMT (rhs1))
+                                   == gimple_bb (SSA_NAME_DEF_STMT (s))))
+                             goto force_name;
+                           break;
+                         default:
+                           break;
+                       }
                      if ((TYPE_PRECISION (TREE_TYPE (rhs1))
                           >= TYPE_PRECISION (TREE_TYPE (s)))
                          && mergeable_op (use_stmt))
@@ -6154,6 +6174,7 @@ gimple_lower_bitint (void)
              && (!SSA_NAME_VAR (s) || VAR_P (SSA_NAME_VAR (s))))
            continue;
 
+       force_name:
          if (!large_huge.m_names)
            large_huge.m_names = BITMAP_ALLOC (NULL);
          bitmap_set_bit (large_huge.m_names, SSA_NAME_VERSION (s));

diff --git a/gcc/testsuite/gcc.dg/bitint-56.c b/gcc/testsuite/gcc.dg/bitint-56.c
new file mode 100644 (file)
index 0000000..ceccd1b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-56.c
@@ -0,0 +1,129 @@
+/* PR tree-optimization/112941 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=c23 -O2" } */
+
+#if __BITINT_MAXWIDTH__ >= 4096
+void
+f1 (_BitInt(4096) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] *= (unsigned _BitInt(2048)) r;
+  p[1] *= (unsigned _BitInt(2048)) s;
+  p[2] *= (unsigned _BitInt(2048)) t;
+  p[3] *= (unsigned _BitInt(2048)) u;
+}
+
+void
+f2 (_BitInt(4094) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] /= (unsigned _BitInt(2048)) r;
+  p[1] /= (unsigned _BitInt(2048)) s;
+  p[2] /= (unsigned _BitInt(2048)) t;
+  p[3] /= (unsigned _BitInt(2048)) u;
+}
+
+void
+f3 (_BitInt(4096) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] *= (unsigned _BitInt(2110)) r;
+  p[1] *= (unsigned _BitInt(2110)) s;
+  p[2] *= (unsigned _BitInt(2110)) t;
+  p[3] *= (unsigned _BitInt(2110)) u;
+}
+
+void
+f4 (_BitInt(4094) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] /= (unsigned _BitInt(2110)) r;
+  p[1] /= (unsigned _BitInt(2110)) s;
+  p[2] /= (unsigned _BitInt(2110)) t;
+  p[3] /= (unsigned _BitInt(2110)) u;
+}
+
+void
+f5 (unsigned _BitInt(4096) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] *= (unsigned _BitInt(2048)) r;
+  p[1] *= (unsigned _BitInt(2048)) s;
+  p[2] *= (unsigned _BitInt(2048)) t;
+  p[3] *= (unsigned _BitInt(2048)) u;
+}
+
+void
+f6 (unsigned _BitInt(4094) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] /= (unsigned _BitInt(2048)) r;
+  p[1] /= (unsigned _BitInt(2048)) s;
+  p[2] /= (unsigned _BitInt(2048)) t;
+  p[3] /= (unsigned _BitInt(2048)) u;
+}
+
+void
+f7 (unsigned _BitInt(4096) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] *= (unsigned _BitInt(2110)) r;
+  p[1] *= (unsigned _BitInt(2110)) s;
+  p[2] *= (unsigned _BitInt(2110)) t;
+  p[3] *= (unsigned _BitInt(2110)) u;
+}
+
+void
+f8 (unsigned _BitInt(4094) *p, int r, _BitInt(115) s, _BitInt(128) t, _BitInt(231) u)
+{
+  p[0] /= (unsigned _BitInt(2110)) r;
+  p[1] /= (unsigned _BitInt(2110)) s;
+  p[2] /= (unsigned _BitInt(2110)) t;
+  p[3] /= (unsigned _BitInt(2110)) u;
+}
+
+#if __SIZEOF_INT128__
+void
+f9 (_BitInt(4096) *p, __int128 r)
+{
+  p[0] *= (unsigned _BitInt(2048)) r;
+}
+
+void
+f10 (_BitInt(4094) *p, __int128 r)
+{
+  p[0] /= (unsigned _BitInt(2048)) r;
+}
+
+void
+f11 (_BitInt(4096) *p, __int128 r)
+{
+  p[0] *= (unsigned _BitInt(2110)) r;
+}
+
+void
+f12 (_BitInt(4094) *p, __int128 r)
+{
+  p[0] /= (unsigned _BitInt(2110)) r;
+}
+
+void
+f13 (unsigned _BitInt(4096) *p, __int128 r)
+{
+  p[0] *= (unsigned _BitInt(2048)) r;
+}
+
+void
+f14 (unsigned _BitInt(4094) *p, __int128 r)
+{
+  p[0] /= (unsigned _BitInt(2048)) r;
+}
+
+void
+f15 (unsigned _BitInt(4096) *p, __int128 r)
+{
+  p[0] *= (unsigned _BitInt(2110)) r;
+}
+
+void
+f16 (unsigned _BitInt(4094) *p, __int128 r)
+{
+  p[0] /= (unsigned _BitInt(2110)) r;
+}
+#endif
+#else
+int i;
+#endif

diff --git a/gcc/testsuite/gcc.dg/bitint-57.c b/gcc/testsuite/gcc.dg/bitint-57.c
new file mode 100644 (file)
index 0000000..1a0d4cc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-57.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/112941 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=c23 -O1 -fno-tree-forwprop" } */
+
+#if __BITINT_MAXWIDTH__ >= 6384
+unsigned _BitInt(2049)
+foo (unsigned _BitInt(6384) x, _BitInt(8) y)
+{
+  unsigned _BitInt(6384) z = y;
+  return x * z;
+}
+
+_BitInt(2049)
+bar (unsigned _BitInt(6384) x, _BitInt(1023) y)
+{
+  unsigned _BitInt(6384) z = y;
+  return x * z;
+}
+#else
+int i;
+#endif