From 38f9900aa5241dd8fcb70dce3543a294d0d3e870 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Sat, 19 Jan 2019 00:33:02 +0000
Subject: [X86] Deduplicate static calling convention helpers for code size,
 NFC

Summary:
Right now we include ${TGT}GenCallingConv.inc once per each instruction
selection method implemented by ${TGT}:
- ${TGT}ISelLowering.cpp
- ${TGT}CallLowering.cpp
- ${TGT}FastISel.cpp

Instead, add a mechanism to tablegen for marking a particular convention
as "External", which causes tablegen to emit into the ::llvm namespace,
instead of as a static helper. This allows us to provide a header to
forward declare it, so we can simply call the function from all the
places it is referenced. Typically the calling convention analyzer is
called indirectly, so it doesn't benefit from inlining.

This saves a bit of final binary size, but mostly just saves object file
size:

before  after   diff   artifact
12852K  12492K  -360K  X86ISelLowering.cpp.obj
4640K   4280K   -360K  X86FastISel.cpp.obj
1704K   2092K   +388K  X86CallingConv.cpp.obj
52448K  52336K  -112K  llc.exe

I didn't collect before numbers for X86CallLowering.cpp.obj, which is
for GlobalISel, but we should save 360K there as well.

This patch applies the strategy to the X86 backend, but there is no
reason it couldn't be applied to the other backends that implement
multiple ISel strategies, like AArch64.

Reviewers: craig.topper, hfinkel, efriedma

Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D56883

llvm-svn: 351616
---
 llvm/utils/TableGen/CallingConvEmitter.cpp | 34 ++++++++++++++++++++----------
 1 file changed, 23 insertions(+), 11 deletions(-)

(limited to 'llvm/utils/TableGen/CallingConvEmitter.cpp')

diff --git a/llvm/utils/TableGen/CallingConvEmitter.cpp b/llvm/utils/TableGen/CallingConvEmitter.cpp
index d452031f885..41cea62f271 100644
--- a/llvm/utils/TableGen/CallingConvEmitter.cpp
+++ b/llvm/utils/TableGen/CallingConvEmitter.cpp
@@ -41,11 +41,17 @@ void CallingConvEmitter::run(raw_ostream &O) {
   // each other.
   for (Record *CC : CCs) {
     if (!CC->getValueAsBit("Custom")) {
-      O << "static bool " << CC->getName()
-        << "(unsigned ValNo, MVT ValVT,\n"
-        << std::string(CC->getName().size() + 13, ' ')
-        << "MVT LocVT, CCValAssign::LocInfo LocInfo,\n"
-        << std::string(CC->getName().size() + 13, ' ')
+      unsigned Pad = CC->getName().size();
+      if (CC->getValueAsBit("Entry")) {
+        O << "bool llvm::";
+        Pad += 12;
+      } else {
+        O << "static bool ";
+        Pad += 13;
+      }
+      O << CC->getName() << "(unsigned ValNo, MVT ValVT,\n"
+        << std::string(Pad, ' ') << "MVT LocVT, CCValAssign::LocInfo LocInfo,\n"
+        << std::string(Pad, ' ')
         << "ISD::ArgFlagsTy ArgFlags, CCState &State);\n";
     }
   }
@@ -62,12 +68,18 @@ void CallingConvEmitter::EmitCallingConv(Record *CC, raw_ostream &O) {
   ListInit *CCActions = CC->getValueAsListInit("Actions");
   Counter = 0;
 
-  O << "\n\nstatic bool " << CC->getName()
-    << "(unsigned ValNo, MVT ValVT,\n"
-    << std::string(CC->getName().size()+13, ' ')
-    << "MVT LocVT, CCValAssign::LocInfo LocInfo,\n"
-    << std::string(CC->getName().size()+13, ' ')
-    << "ISD::ArgFlagsTy ArgFlags, CCState &State) {\n";
+  O << "\n\n";
+  unsigned Pad = CC->getName().size();
+  if (CC->getValueAsBit("Entry")) {
+    O << "bool llvm::";
+    Pad += 12;
+  } else {
+    O << "static bool ";
+    Pad += 13;
+  }
+  O << CC->getName() << "(unsigned ValNo, MVT ValVT,\n"
+    << std::string(Pad, ' ') << "MVT LocVT, CCValAssign::LocInfo LocInfo,\n"
+    << std::string(Pad, ' ') << "ISD::ArgFlagsTy ArgFlags, CCState &State) {\n";
   // Emit all of the actions, in order.
   for (unsigned i = 0, e = CCActions->size(); i != e; ++i) {
     O << "\n";
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