PNaCl wire format: Remove the top-level DATALAYOUT record

PNaCl only supports a fixed data layout, so treat this as implicit in
the pexe file.

Add the data layout field back at read time, to prevent accidentally
using any architecture-specific backend data layout when translating,
and to ensure that any IR passes that use the data layout work
correctly.

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3505
TEST=*.ll tests + PNaCl toolchain trybots

Review URL: https://codereview.chromium.org/17591014

1 files changed, 10 insertions, 7 deletions

diff --git a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
index 8fe6274a15..bd6ddcb020 100644
--- a/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
+++ b/lib/Bitcode/NaCl/Reader/NaClBitcodeReader.cpp
@@ -1477,13 +1477,6 @@ bool NaClBitcodeReader::ParseModule(bool Resume) {
       }
       break;
     }
-    case naclbitc::MODULE_CODE_DATALAYOUT: {  // DATALAYOUT: [strchr x N]
-      std::string S;
-      if (ConvertToString(Record, 0, S))
-        return Error("Invalid MODULE_CODE_DATALAYOUT record");
-      TheModule->setDataLayout(S);
-      break;
-    }
     case naclbitc::MODULE_CODE_ASM: {  // ASM: [strchr x N]
       std::string S;
       if (ConvertToString(Record, 0, S))
@@ -1630,6 +1623,16 @@ bool NaClBitcodeReader::ParseModule(bool Resume) {
 bool NaClBitcodeReader::ParseBitcodeInto(Module *M) {
   TheModule = 0;
 
+  // PNaCl does not support different DataLayouts in pexes, so we
+  // implicitly set the DataLayout to the following default.
+  //
+  // This is not usually needed by the backend, but it might be used
+  // by IR passes that the PNaCl translator runs.  We set this in the
+  // reader rather than in pnacl-llc so that 'opt' will also use the
+  // correct DataLayout if it is run on a pexe.
+  M->setDataLayout("e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-"
+                   "f32:32:32-f64:64:64-p:32:32:32-v128:32:32");
+
   if (InitStream()) return true;
 
   // We expect a number of well-defined blocks, though we don't necessarily