target/i386: tcg: simplify computation of AF after INC/DEC

No difference in generated code, but the XOR-based formula is
easily understood on its own.  This will make more sense once
ADD/SUB stop using dst^src1^src2 to compute AF.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/tcg/cc_helper_template.h.inc b/target/i386/tcg/cc_helper_template.h.inc
index 9aff16b88012c138f9241b781326d6ac998cc985..b821e5bca3b2c094f148bcee540f952dcadcb8b5 100644 (file)
--- a/target/i386/tcg/cc_helper_template.h.inc
+++ b/target/i386/tcg/cc_helper_template.h.inc
@@ -175,13 +175,10 @@ static uint32_t glue(compute_all_logic, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
 static uint32_t glue(compute_all_inc, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
 {
     uint32_t cf, pf, af, zf, sf, of;
-    DATA_TYPE src2;
 
     cf = src1;
-    src1 = dst - 1;
-    src2 = 1;
     pf = compute_pf(dst);
-    af = (dst ^ src1 ^ src2) & CC_A;
+    af = (dst ^ (dst - 1)) & CC_A; /* bits 0..3 are all clear */
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
     of = (dst == SIGN_MASK) * CC_O;
@@ -191,13 +188,10 @@ static uint32_t glue(compute_all_inc, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
 static uint32_t glue(compute_all_dec, SUFFIX)(DATA_TYPE dst, DATA_TYPE src1)
 {
     uint32_t cf, pf, af, zf, sf, of;
-    DATA_TYPE src2;
 
     cf = src1;
-    src1 = dst + 1;
-    src2 = 1;
     pf = compute_pf(dst);
-    af = (dst ^ src1 ^ src2) & CC_A;
+    af = (dst ^ (dst + 1)) & CC_A; /* bits 0..3 are all set */
     zf = (dst == 0) * CC_Z;
     sf = lshift(dst, 8 - DATA_BITS) & CC_S;
     of = (dst == SIGN_MASK - 1) * CC_O;