From: Christoph Mallon <christoph.mallon@gmx.de>
Date: Sat, 8 May 2010 21:04:43 +0000 (+0000)
Subject: Clarify the carry testing magic.
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=7dc7d79b63f1787e087174ee6a7313b7658fe799;p=libfirm

Clarify the carry testing magic.

[r27516]
---

diff --git a/ir/be/ia32/ia32_nodes_attr.h b/ir/be/ia32/ia32_nodes_attr.h
index fc53e6d0f..9b4012370 100644
--- a/ir/be/ia32/ia32_nodes_attr.h
+++ b/ir/be/ia32/ia32_nodes_attr.h
@@ -32,9 +32,12 @@
 #include "irnode_t.h"
 
 enum {
-	ia32_pn_Cmp_unsigned = 0x1000,
-	ia32_pn_Cmp_float    = 0x2000,
-	ia32_pn_Cmp_parity   = 0x4000
+	ia32_pn_Cmp_unsigned  = 0x1000,
+	ia32_pn_Cmp_float     = 0x2000,
+	ia32_pn_Cmp_parity    = 0x4000,
+	/* The unsigned Lt/Ge comparisons test the carry bit. */
+	ia32_pn_Cmp_carry     = pn_Cmp_Lt | ia32_pn_Cmp_unsigned
+	ia32_pn_Cmp_not_carry = pn_Cmp_Ge | ia32_pn_Cmp_unsigned,
 };
 
 typedef enum {
diff --git a/ir/be/ia32/ia32_optimize.c b/ir/be/ia32/ia32_optimize.c
index 0334f34b0..801f8aa1b 100644
--- a/ir/be/ia32/ia32_optimize.c
+++ b/ir/be/ia32/ia32_optimize.c
@@ -265,8 +265,8 @@ static void peephole_ia32_Test(ir_node *node)
 					int      pnc  = get_ia32_condcode(user);
 
 					switch (pnc) {
-						case pn_Cmp_Eq: pnc = pn_Cmp_Ge | ia32_pn_Cmp_unsigned; break;
-						case pn_Cmp_Lg: pnc = pn_Cmp_Lt | ia32_pn_Cmp_unsigned; break;
+						case pn_Cmp_Eq: pnc = ia32_pn_Cmp_no_carry; break;
+						case pn_Cmp_Lg: pnc = ia32_pn_Cmp_carry;    break;
 						default: panic("unexpected pn");
 					}
 					set_ia32_condcode(user, pnc);