From: Rhys Weatherley <rweather@southern-storm.com.au>
Date: Wed, 2 Jun 2004 07:29:47 +0000 (+0000)
Subject: _jit_regs_load_value: if a value is in a global register and it is
X-Git-Tag: r.0.0.4~58
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=8bc5c7af871eb5eb590653e643b38fe130f3f1f1;p=francis%2Flibjit.git

_jit_regs_load_value: if a value is in a global register and it is
not going to be destroyed by an instruction, then use the global
register as the operand.
---

diff --git a/ChangeLog b/ChangeLog
index 992ede1..5f974f5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -8,6 +8,10 @@
 	jit/jit-value.c, tools/gen-sel-parser.y: implement a simple global
 	register allocation policy, based on usage counts.
 
+	* jit/jit-reg-alloc.c (_jit_regs_load_value): if a value is in a
+	global register and it is not going to be destroyed by an instruction,
+	then use the global register as the operand.
+
 2004-06-01  Rhys Weatherley  <rweather@southern-storm.com.au>
 
 	* jit/jit-cache.c, jit/jit-elf-read.c, tools/gen-apply.c:
diff --git a/jit/jit-reg-alloc.c b/jit/jit-reg-alloc.c
index c003095..190c01b 100644
--- a/jit/jit-reg-alloc.c
+++ b/jit/jit-reg-alloc.c
@@ -1026,6 +1026,14 @@ int _jit_regs_load_value
 		}
 	}
 
+	/* If the value is in a global register, and we are not going
+	   to destroy the value, then use the global register itself.
+	   This will avoid a redundant register copy operation */
+	if(value->in_global_register && !destroy)
+	{
+		return value->global_reg;
+	}
+
 	/* Search for a free register to hold the value */
 	reg = free_register_for_value(gen, value, &other_reg);
 	load_value(gen, reg, other_reg, value, destroy);