From db4cafa6c40a4ea99643642dd5f2532bc0745eea Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter@pcc.me.uk>
Date: Thu, 6 Apr 2017 19:39:24 +0000
Subject: [PATCH] Bitcode: Do not create FNENTRYs for aliases of functions.

There doesn't seem to be any point in doing this.

Differential Revision: https://reviews.llvm.org/D31691

llvm-svn: 299694
---
 llvm/lib/Bitcode/Reader/BitcodeReader.cpp     | 16 +++++-----------
 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp     |  7 -------
 llvm/test/Bitcode/thinlto-function-summary.ll |  2 +-
 3 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 23649e811ede..80a2c918916b 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1796,22 +1796,16 @@ Error BitcodeReader::parseValueSymbolTable(uint64_t Offset) {
         return Err;
       Value *V = ValOrErr.get();
 
-      auto *GO = dyn_cast<GlobalObject>(V);
-      if (!GO) {
-        // If this is an alias, need to get the actual Function object
-        // it aliases, in order to set up the DeferredFunctionInfo entry below.
-        auto *GA = dyn_cast<GlobalAlias>(V);
-        if (GA)
-          GO = GA->getBaseObject();
-        assert(GO);
-      }
+      auto *F = dyn_cast<Function>(V);
+      // Ignore function offsets emitted for aliases of functions in older
+      // versions of LLVM.
+      if (!F)
+        break;
 
       // Note that we subtract 1 here because the offset is relative to one word
       // before the start of the identification or module block, which was
       // historically always the start of the regular bitcode header.
       uint64_t FuncWordOffset = Record[1] - 1;
-      Function *F = dyn_cast<Function>(GO);
-      assert(F);
       uint64_t FuncBitOffset = FuncWordOffset * 32;
       DeferredFunctionInfo[F] = FuncBitOffset + FuncBitcodeOffsetDelta;
       // Set the LastFunctionBlockBit to point to the last function block.
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index be1c5521018a..7b494d4b9dd4 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -2924,13 +2924,6 @@ void ModuleBitcodeWriter::writeValueSymbolTable(
     NameVals.push_back(VE.getValueID(Name.getValue()));
 
     Function *F = dyn_cast<Function>(Name.getValue());
-    if (!F) {
-      // If value is an alias, need to get the aliased base object to
-      // see if it is a function.
-      auto *GA = dyn_cast<GlobalAlias>(Name.getValue());
-      if (GA && GA->getBaseObject())
-        F = dyn_cast<Function>(GA->getBaseObject());
-    }
 
     // VST_CODE_ENTRY:   [valueid, namechar x N]
     // VST_CODE_FNENTRY: [valueid, funcoffset, namechar x N]
diff --git a/llvm/test/Bitcode/thinlto-function-summary.ll b/llvm/test/Bitcode/thinlto-function-summary.ll
index 594aaab566d1..ff61b7713f0f 100644
--- a/llvm/test/Bitcode/thinlto-function-summary.ll
+++ b/llvm/test/Bitcode/thinlto-function-summary.ll
@@ -17,7 +17,7 @@
 ; BC-NEXT: <FNENTRY {{.*}} op0=4 {{.*}}> record string = 'variadic'
 ; BC-NEXT: <FNENTRY {{.*}} op0=1 {{.*}}> record string = 'foo'
 ; BC-NEXT: <FNENTRY {{.*}} op0=2 {{.*}}> record string = 'bar'
-; BC-NEXT: <FNENTRY {{.*}} op0=5 {{.*}}> record string = 'f'
+; BC-NEXT: <ENTRY {{.*}} op0=5 {{.*}}> record string = 'f'
 ; BC-NEXT: <ENTRY {{.*}} record string = 'h'
 ; BC-NEXT: <FNENTRY {{.*}} op0=3 {{.*}}> record string = 'anon.