Convert constant conditional branches such as "if true goto L" into

ChangeLog

@@ -1,4 +1,10 @@
 
+2004-05-20  Rhys Weatherley  <rweather@southern-storm.com.au>
+
+	* include/jit/jit-value.h, jit/jit-insn.c, jit/jit-value.c:
+	convert constant conditional branches such as "if true goto L" into
+	unconditional branches.
+
 2004-05-15  Rhys Weatherley  <rweather@southern-storm.com.au>
 
 	* tools/gen-apply.c: fix a macro generation bug for Win32 systems.

include/jit/jit-value.h

@@ -90,6 +90,7 @@ jit_long jit_value_get_long_constant(jit_value_t value) JIT_NOTHROW;
 jit_float32 jit_value_get_float32_constant(jit_value_t value) JIT_NOTHROW;
 jit_float64 jit_value_get_float64_constant(jit_value_t value) JIT_NOTHROW;
 jit_nfloat jit_value_get_nfloat_constant(jit_value_t value) JIT_NOTHROW;
+int jit_value_is_true(jit_value_t value) JIT_NOTHROW;
 int jit_constant_convert
 	(jit_constant_t *result, const jit_constant_t *value,
 	 jit_type_t type, int overflow_check) JIT_NOTHROW;

jit/jit-insn.c

@@ -3547,6 +3547,20 @@ int jit_insn_branch_if
 		*label = (func->builder->next_label)++;
 	}
 
+	/* If the condition is constant, then convert it into either
+	   an unconditional branch or a fall-through, as appropriate */
+	if(jit_value_is_constant(value))
+	{
+		if(jit_value_is_true(value))
+		{
+			return jit_insn_branch(func, label);
+		}
+		else
+		{
+			return 1;
+		}
+	}
+
 	/* Determine if we can replace a previous comparison instruction */
 	block = func->builder->current_block;
 	insn = _jit_block_get_last(block);
@@ -3734,6 +3748,20 @@ int jit_insn_branch_if_not
 		*label = (func->builder->next_label)++;
 	}
 
+	/* If the condition is constant, then convert it into either
+	   an unconditional branch or a fall-through, as appropriate */
+	if(jit_value_is_constant(value))
+	{
+		if(!jit_value_is_true(value))
+		{
+			return jit_insn_branch(func, label);
+		}
+		else
+		{
+			return 1;
+		}
+	}
+
 	/* Determine if we can replace a previous comparison instruction */
 	block = func->builder->current_block;
 	insn = _jit_block_get_last(block);

jit/jit-value.c

@@ -929,6 +929,66 @@ jit_nfloat jit_value_get_nfloat_constant(jit_value_t value)
 	return (jit_nfloat)0.0;
 }
 
+/*@
+ * @deftypefun int jit_value_is_true (jit_value_t value)
+ * Determine if @code{value} is constant and non-zero.
+ * @end deftypefun
+@*/
+int jit_value_is_true(jit_value_t value)
+{
+	if(!value || !(value->is_constant))
+	{
+		return 0;
+	}
+	else if(value->is_nint_constant)
+	{
+		return (value->address != 0);
+	}
+	else
+	{
+		switch(jit_type_normalize(value->type)->kind)
+		{
+			case JIT_TYPE_LONG:
+			case JIT_TYPE_ULONG:
+			{
+				if(jit_value_get_long_constant(value) != 0)
+				{
+					return 1;
+				}
+			}
+			break;
+
+			case JIT_TYPE_FLOAT32:
+			{
+				if(jit_value_get_float32_constant(value) != (jit_float32)0.0)
+				{
+					return 1;
+				}
+			}
+			break;
+
+			case JIT_TYPE_FLOAT64:
+			{
+				if(jit_value_get_float64_constant(value) != (jit_float64)0.0)
+				{
+					return 1;
+				}
+			}
+			break;
+
+			case JIT_TYPE_NFLOAT:
+			{
+				if(jit_value_get_nfloat_constant(value) != (jit_nfloat)0.0)
+				{
+					return 1;
+				}
+			}
+			break;
+		}
+		return 0;
+	}
+}
+
 /*@
  * @deftypefun int jit_constant_convert ({jit_constant_t *} result, {const jit_constant_t *} value, jit_type_t type, int overflow_check)
  * Convert a the constant @code{value} into a new @code{type}, and