Use correct size_t when determining if a value fits in a byte (#42987)

- Use target_size_t when determining if a value fits in a byte when value is represented in the function as a ssize_t or cnssval_ssize_t. This drops the upper 32bits of a possibly 64bit size_t when performing the comparison on TARGET_X86 platforms. Those bits are uninitialized if the value not a reloc.

diff --git a/src/coreclr/src/jit/emitxarch.cpp b/src/coreclr/src/jit/emitxarch.cpp
index 58af8ad..0a6c7ae 100644 (file)
--- a/src/coreclr/src/jit/emitxarch.cpp
+++ b/src/coreclr/src/jit/emitxarch.cpp
@@ -3825,7 +3825,7 @@ void emitter::emitIns_R_I(instruction ins, emitAttr attr, regNumber reg, ssize_t
     UNATIVE_OFFSET sz;
     instrDesc*     id;
     insFormat      fmt       = emitInsModeFormat(ins, IF_RRD_CNS);
-    bool           valInByte = ((signed char)val == val) && (ins != INS_mov) && (ins != INS_test);
+    bool           valInByte = ((signed char)val == (target_ssize_t)val) && (ins != INS_mov) && (ins != INS_test);
 
     // BT reg,imm might be useful but it requires special handling of the immediate value
     // (it is always encoded in a byte). Let's not complicate things until this is needed.
@@ -3952,7 +3952,7 @@ void emitter::emitIns_I(instruction ins, emitAttr attr, cnsval_ssize_t val)
 {
     UNATIVE_OFFSET sz;
     instrDesc*     id;
-    bool           valInByte = ((signed char)val == val);
+    bool           valInByte = ((signed char)val == (target_ssize_t)val);
 
 #ifdef TARGET_AMD64
     // mov reg, imm64 is the only opcode which takes a full 8 byte immediate
@@ -11760,7 +11760,7 @@ BYTE* emitter::emitOutputRI(BYTE* dst, instrDesc* id)
     instruction ins       = id->idIns();
     regNumber   reg       = id->idReg1();
     ssize_t     val       = emitGetInsSC(id);
-    bool        valInByte = ((signed char)val == val) && (ins != INS_mov) && (ins != INS_test);
+    bool        valInByte = ((signed char)val == (target_ssize_t)val) && (ins != INS_mov) && (ins != INS_test);
 
     // BT reg,imm might be useful but it requires special handling of the immediate value
     // (it is always encoded in a byte). Let's not complicate things until this is needed.
@@ -12111,7 +12111,7 @@ BYTE* emitter::emitOutputIV(BYTE* dst, instrDesc* id)
     instruction ins       = id->idIns();
     emitAttr    size      = id->idOpSize();
     ssize_t     val       = emitGetInsSC(id);
-    bool        valInByte = ((signed char)val == val);
+    bool        valInByte = ((signed char)val == (target_ssize_t)val);
 
     // We would to update GC info correctly
     assert(!IsSSEInstruction(ins));