From bbdf78c061b6e685d1992dcdeac692fc2f8f0d34 Mon Sep 17 00:00:00 2001
From: iximeow <me@iximeow.net>
Date: Mon, 1 Apr 2024 23:38:57 -0700
Subject: display opt: mem size labels and minor segment reporting changes

for mem size labels: add one new "BUG" entry at the start of the array
  so `mem_size` does not need to be adjusted before being used to look
  up a string from the `MEM_SIZE_STRINGS` array. it's hard to measure
  the direct benefit of this, but it shrinks codegen size by a bit and
  simplfies a bit of assembly....

for segment reporting changes: stos/scas/lods do not actually need
  special segment override logic. instead, set their use of `es` when
  decoded, if appropriate. this is potentially ambiguous; in non-64bit
  modes the sequence `26aa` would decode as `stos` with explicit `es`
  prefix. this is now identical to simply decoding `aa`, which now also
  reports that there is an explicit `es` prefix even though there is no
  prefix on tne instruction.

  on the other hand, the prefix-reported segment now more accurately
  describes the memory selector through which memory accesses will
  happen. seems ok?
---
 src/long_mode/mod.rs | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

(limited to 'src/long_mode/mod.rs')

diff --git a/src/long_mode/mod.rs b/src/long_mode/mod.rs
index 9bc9f0b..f58976a 100644
--- a/src/long_mode/mod.rs
+++ b/src/long_mode/mod.rs
@@ -4380,21 +4380,6 @@ impl Instruction {
     /// prefixes.
     pub fn segment_override_for_op(&self, op: u8) -> Option<Segment> {
         match self.opcode {
-            Opcode::STOS |
-            Opcode::SCAS => {
-                if op == 0 {
-                    Some(Segment::ES)
-                } else {
-                    None
-                }
-            }
-            Opcode::LODS => {
-                if op == 1 {
-                    Some(self.prefixes.segment)
-                } else {
-                    None
-                }
-            }
             Opcode::MOVS => {
                 if op == 0 {
                     Some(Segment::ES)
@@ -9002,6 +8987,7 @@ fn read_operands<
         }
         OperandCase::Yb_AL => {
             instruction.regs[0] = RegSpec::al();
+            instruction.prefixes.segment = Segment::ES;
             if instruction.prefixes.address_size() {
                 instruction.regs[1] = RegSpec::edi();
             } else {
@@ -9028,6 +9014,7 @@ fn read_operands<
             let bank = bank_from_prefixes_64(SizeCode::vqp, instruction.prefixes);
             instruction.regs[0].num = 0;
             instruction.regs[0].bank = bank;
+            instruction.prefixes.segment = Segment::ES;
             if instruction.prefixes.address_size() {
                 instruction.regs[1] = RegSpec::edi();
             } else {
-- 
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