From: Aleksey Demakov <ademakov@gmail.com>
Date: Wed, 25 Mar 2009 17:33:48 +0000 (+0000)
Subject: arm fixes
X-Git-Tag: before.move.to.git~22
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=944b23f5e146cabfa4cfc708551129a86a42ab2f;p=francis%2Flibjit.git

arm fixes
---

diff --git a/ChangeLog b/ChangeLog
index 259ec64..bdff4fd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2009-03-25  Michele Tartara  <mikyt@users.sourceforge.net>
+
+	* jit/jit-gen-arm.h (arm_alu_cc_reg): fix a typo.
+	* jit/jit-rules-arm.ins (JIT_OP_IDIV): support negative dividends.
+
 2009-03-24  Aleksey Demakov  <ademakov@gmail.com>
 
 	* jit/jit-rules.h (jit_reg_other_reg): add macro.
diff --git a/jit/jit-gen-arm.h b/jit/jit-gen-arm.h
index 88bcfd3..754911b 100644
--- a/jit/jit-gen-arm.h
+++ b/jit/jit-gen-arm.h
@@ -421,7 +421,7 @@ extern void _arm_alu_reg_imm
 			} while (0)
 #define arm_alu_cc_reg(inst,opc,dreg,sreg)	\
 			do { \
-				arm_inst_add((inst), = arm_execute_cc | \
+				arm_inst_add((inst), arm_execute_cc | \
 							(((unsigned int)(opc)) << 21) | \
 							(((unsigned int)(dreg)) << 12) | \
 							 ((unsigned int)(sreg))); \
diff --git a/jit/jit-rules-arm.ins b/jit/jit-rules-arm.ins
index 145e834..b676352 100644
--- a/jit/jit-rules-arm.ins
+++ b/jit/jit-rules-arm.ins
@@ -189,8 +189,16 @@ JIT_OP_IDIV:
 	[reg, immu8, if("$2 == 1")] -> {
 		/* Division by 1. Return the value itself */
 	}
-	[reg, immu8, if("($2 % 2) == 0")] -> {
-		/* Handle special cases of small immediate divides */
+	[reg, immu8, if("($2 > 0) && (((jit_nuint)$2) & (((jit_nuint)$2) - 1)) == 0")] -> {
+		/* Handle special cases of small immediate divides: divisions by positive powers of two */
+		/* NB: (n & (n-1)) == 0 if and only if n is a power of 2 */
+		
+		/* Move the dividend in the work register, setting the codes (in order to know if it's positive or negative) */
+		arm_alu_cc_reg(inst, ARM_MOV, ARM_WORK, $1);
+
+		/* If the dividend is negative, make it positive (0-x = -x)*/
+		arm_alu_reg_imm8_cond(inst, ARM_RSB, $1, ARM_WORK, 0, ARM_CC_MI);
+
 		switch($2)
 		{
 			//Integer divide by shifting
@@ -236,6 +244,10 @@ JIT_OP_IDIV:
 			}
 			break;
 		}
+		
+		/* If the dividend was negative, make it negative again (0-x = -x)*/
+		arm_alu_reg_imm8_cond(inst, ARM_RSB, $1, $1, 0, ARM_CC_MI);
+		
 	}
 	[reg, imm, if("$2 == -1")] -> {
 		/* Dividing by -1 simply negates */