commit b61a4aaca5f8a1e71eeaee74d93cdd6fccbef065
author Fangrui Song <maskray@google.com> Mon Feb 24 18:09:27 2020 -0800
committer Fangrui Song <maskray@google.com> Tue Feb 25 18:23:10 2020 -0800
tree 483f865c2f4d1cf9173915c1ffaf6f4aca0768dc
parent d0c4277d388628154b647a45cbc6914a1ea5a822

[MC] Default MCContext::UseNamesOnTempLabels to false and only set it to true for MCAsmStreamer

Only MCAsmStreamer (assembly output) needs to keep names of temporary labels created by
MCContext::createTempSymbol().

This change made the rL236642 optimization available for cc2as and
probably some other users.

This eliminates a behavior difference between llvm-mc -filetype=obj and cc1as, which caused
https://reviews.llvm.org/D74006#1890487

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D75097

llvm/include/llvm/MC/MCContext.h

diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index 7d29979..9e02bd1 100644
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -188,7 +188,7 @@
     /// differences between temporary and non-temporary labels (primarily on
     /// Darwin).
     bool AllowTemporaryLabels = true;
-    bool UseNamesOnTempLabels = true;
+    bool UseNamesOnTempLabels = false;
 
     /// The Compile Unit ID that we are currently processing.
     unsigned DwarfCompileUnitID = 0;

llvm/lib/CodeGen/LLVMTargetMachine.cpp

diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index 50c178f..b485f2c 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -157,9 +157,6 @@
     if (!MCE || !MAB)
       return true;
 
-    // Don't waste memory on names of temp labels.
-    Context.setUseNamesOnTempLabels(false);
-
     Triple T(getTargetTriple().str());
     AsmStreamer.reset(getTarget().createMCObjectStreamer(
         T, Context, std::unique_ptr<MCAsmBackend>(MAB),

llvm/lib/MC/MCAsmStreamer.cpp

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 9281584..3792655 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -79,6 +79,8 @@
         InstPrinter->setCommentStream(CommentStream);
     if (Assembler->getBackendPtr())
       setAllowAutoPadding(Assembler->getBackend().allowAutoPadding());
+
+    Context.setUseNamesOnTempLabels(true);
   }
 
   MCAssembler &getAssembler() { return *Assembler; }

llvm/tools/llvm-mc/llvm-mc.cpp

diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp
index 25f02b9..dadb7f5 100644
--- a/llvm/tools/llvm-mc/llvm-mc.cpp
+++ b/llvm/tools/llvm-mc/llvm-mc.cpp
@@ -474,9 +474,6 @@
   } else {
     assert(FileType == OFT_ObjectFile && "Invalid file type!");
 
-    // Don't waste memory on names of temp labels.
-    Ctx.setUseNamesOnTempLabels(false);
-
     if (!Out->os().supportsSeeking()) {
       BOS = std::make_unique<buffer_ostream>(Out->os());
       OS = BOS.get();

llvm/tools/llvm-ml/llvm-ml.cpp

diff --git a/llvm/tools/llvm-ml/llvm-ml.cpp b/llvm/tools/llvm-ml/llvm-ml.cpp
index 2e8ecd9..5eefc1e 100644
--- a/llvm/tools/llvm-ml/llvm-ml.cpp
+++ b/llvm/tools/llvm-ml/llvm-ml.cpp
@@ -333,9 +333,6 @@
   } else {
     assert(FileType == OFT_ObjectFile && "Invalid file type!");
 
-    // Don't waste memory on names of temp labels.
-    Ctx.setUseNamesOnTempLabels(false);
-
     if (!Out->os().supportsSeeking()) {
       BOS = std::make_unique<buffer_ostream>(Out->os());
       OS = BOS.get();