From 0b8898400515e9bfaca2a782b2fc899aac69110f Mon Sep 17 00:00:00 2001
From: Ryan Houdek <Sonicadvance1@gmail.com>
Date: Mon, 11 May 2020 16:10:50 -0700
Subject: [PATCH] Fixes a bug in the frontend regarding constants

Optimization passes found a bug in the frontend regarding constants.

Specifically in the case of instructions that have a 32bit constant that
are sign extended to 64bit was being incorrectly set to have a size of
32bits (the size of the constant).
So an optimization pass would rematerialize constants of the expected
size, thus ~0ULL would turn in to ~0U and generate invalid code.

Now watch the destination size and set the constant to that size, which
matches what its size will be.
---
 External/FEXCore/Source/Interface/Core/Frontend.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/External/FEXCore/Source/Interface/Core/Frontend.cpp b/External/FEXCore/Source/Interface/Core/Frontend.cpp
index b0934821f..0ed63a6cb 100644
--- a/External/FEXCore/Source/Interface/Core/Frontend.cpp
+++ b/External/FEXCore/Source/Interface/Core/Frontend.cpp
@@ -221,6 +221,8 @@ bool Decoder::NormalOp(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op)
   LogMan::Throw::A(!(Info->Type >= FEXCore::X86Tables::TYPE_GROUP_1 && Info->Type <= FEXCore::X86Tables::TYPE_GROUP_P),
     "Group Ops should have been decoded before this!");
 
+  uint8_t DestSize{};
+
   // New instruction size decoding
   {
     // Decode destinations first
@@ -229,12 +231,15 @@ bool Decoder::NormalOp(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op)
 
     if (DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_8BIT) {
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_8BIT);
+      DestSize = 1;
     }
     else if (DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_16BIT) {
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_16BIT);
+      DestSize = 2;
     }
     else if (DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_128BIT) {
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_128BIT);
+      DestSize = 16;
     }
     else if (DecodeInst->Flags & DecodeFlags::FLAG_OPERAND_SIZE &&
       (DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_DEF ||
@@ -242,14 +247,17 @@ bool Decoder::NormalOp(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op)
       // See table 1-2. Operand-Size Overrides for this decoding
       // If the default operating mode is 32bit and we have the operand size flag then the operating size drops to 16bit
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_16BIT);
+      DestSize = 2;
     }
     else if (DecodeInst->Flags & DecodeFlags::FLAG_REX_WIDENING ||
       DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_64BIT ||
       DstSizeFlag == FEXCore::X86Tables::InstFlags::SIZE_64BITDEF) {
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_64BIT);
+      DestSize = 8;
     }
     else {
       DecodeInst->Flags |= DecodeFlags::GenSizeDstSize(DecodeFlags::SIZE_32BIT);
+      DestSize = 4;
     }
 
     // Decode sources
@@ -468,7 +476,7 @@ bool Decoder::NormalOp(FEXCore::X86Tables::X86InstInfo const *Info, uint16_t Op)
   if (Bytes != 0) {
     LogMan::Throw::A(Bytes <= 8, "Number of bytes should be <= 8 for literal src");
 
-    DecodeInst->Src[CurrentSrc].TypeLiteral.Size = Bytes;
+    DecodeInst->Src[CurrentSrc].TypeLiteral.Size = DestSize;
 
     uint64_t Literal {0};
     Literal = ReadData(Bytes);