Add saturating float truncation operators (#573)

Add saturating truncation operators as described here:
https://github.com/webassembly/nontrapping-float-to-int-conversions.

This change also codifies the mechanism for enabling new WebAssembly features
by passing the `Features` object. Opcode now has a `IsEnabled(const Features&)`
member function to query if the opcode is enabled. This means that the
`--future-exceptions` flag has been renamed to `--enable-exceptions` for
consistency. Checking whether the feature is enabled always happens at input;
either WastParser or BinaryReader.

1 files changed, 9 insertions, 6 deletions

diff --git a/src/binary-reader-objdump.cc b/src/binary-reader-objdump.cc
index f295a020..ad8f600f 100644
--- a/src/binary-reader-objdump.cc
+++ b/src/binary-reader-objdump.cc
@@ -70,7 +70,6 @@ BinaryReaderObjdumpBase::BinaryReaderObjdumpBase(const uint8_t* data,
       data(data),
       size(size) {
   ZeroMemory(section_starts);
-  BinaryReaderNop::allow_future_exceptions = options->allow_future_exceptions;
 }
 
 Result BinaryReaderObjdumpBase::BeginSection(BinarySection section_code,
@@ -211,7 +210,7 @@ class BinaryReaderObjdumpDisassemble : public BinaryReaderObjdumpBase {
 
   Opcode current_opcode = Opcode::Unreachable;
   Offset current_opcode_offset = 0;
-  size_t last_opcode_end = 0;
+  Offset last_opcode_end = 0;
   int indent_level = 0;
   Index next_reloc = 0;
 };
@@ -223,7 +222,7 @@ Result BinaryReaderObjdumpDisassemble::OnOpcode(Opcode opcode) {
   }
 
   if (last_opcode_end) {
-    if (state->offset != last_opcode_end + 1) {
+    if (state->offset != last_opcode_end + opcode.GetLength()) {
       Opcode missing_opcode = Opcode::FromCode(data[last_opcode_end]);
       const char* opcode_name = missing_opcode.GetName();
       fprintf(stderr,
@@ -249,12 +248,16 @@ void BinaryReaderObjdumpDisassemble::LogOpcode(const uint8_t* data,
   Offset offset = current_opcode_offset;
 
   // Print binary data
-  printf(" %06" PRIzx ": %02x", offset - 1, current_opcode.GetCode());
+  printf(" %06" PRIzx ":", offset - 1);
+  if (current_opcode.HasPrefix())
+    printf(" %02x", current_opcode.GetPrefix());
+  printf(" %02x", current_opcode.GetCode());
   for (size_t i = 0; i < data_size && i < IMMEDIATE_OCTET_COUNT;
        i++, offset++) {
     printf(" %02x", data[offset]);
   }
-  for (size_t i = data_size + 1; i < IMMEDIATE_OCTET_COUNT; i++) {
+  for (size_t i = data_size + current_opcode.GetLength();
+       i < IMMEDIATE_OCTET_COUNT; i++) {
     printf("   ");
   }
   printf(" | ");
@@ -1102,7 +1105,7 @@ Result ReadBinaryObjdump(const uint8_t* data,
   ReadBinaryOptions read_options;
   read_options.read_debug_names = true;
   read_options.log_stream = options->log_stream;
-  read_options.allow_future_exceptions = options->allow_future_exceptions;
+  read_options.features = options->features;
 
   switch (options->mode) {
     case ObjdumpMode::Prepass: {