From ac46827cba75730673aa87f257e6669daa291490 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Wed, 11 Apr 2018 18:05:17 +0000
Subject: [PATCH] [X86] Generalize X86PadShortFunction to work with
 TargetSchedModel

Pre-commit for D45486, don't rely on itinerary scheduler model to determine latencies for padding, use the generic TargetSchedModel::computeInstrLatency call.

Also, replace hard coded (atom specific) 2*uop creation per padding cycle with a version based on the scheduler model's issue width.

Differential Revision: https://reviews.llvm.org/D45486

llvm-svn: 329834
---
 lib/Target/X86/X86PadShortFunction.cpp | 28 +++++++++++---------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/lib/Target/X86/X86PadShortFunction.cpp b/lib/Target/X86/X86PadShortFunction.cpp
index 1da0fad8b6c..2fe5cb973da 100644
--- a/lib/Target/X86/X86PadShortFunction.cpp
+++ b/lib/Target/X86/X86PadShortFunction.cpp
@@ -21,7 +21,7 @@
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/Passes.h"
-#include "llvm/CodeGen/TargetInstrInfo.h"
+#include "llvm/CodeGen/TargetSchedule.h"
 #include "llvm/IR/Function.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -49,7 +49,7 @@ namespace {
   struct PadShortFunc : public MachineFunctionPass {
     static char ID;
     PadShortFunc() : MachineFunctionPass(ID)
-                   , Threshold(4), STI(nullptr), TII(nullptr) {}
+                   , Threshold(4) {}
 
     bool runOnMachineFunction(MachineFunction &MF) override;
 
@@ -82,8 +82,7 @@ namespace {
     // VisitedBBs - Cache of previously visited BBs.
     DenseMap<MachineBasicBlock*, VisitedBBInfo> VisitedBBs;
 
-    const X86Subtarget *STI;
-    const TargetInstrInfo *TII;
+    TargetSchedModel TSM;
   };
 
   char PadShortFunc::ID = 0;
@@ -99,15 +98,13 @@ bool PadShortFunc::runOnMachineFunction(MachineFunction &MF) {
   if (skipFunction(MF.getFunction()))
     return false;
 
-  if (MF.getFunction().optForSize()) {
-    return false;
-  }
-
-  STI = &MF.getSubtarget<X86Subtarget>();
-  if (!STI->padShortFunctions())
+  if (MF.getFunction().optForSize())
     return false;
 
-  TII = STI->getInstrInfo();
+  if (!MF.getSubtarget<X86Subtarget>().padShortFunctions())
+    return false;
+
+  TSM.init(&MF.getSubtarget());
 
   // Search through basic blocks and mark the ones that have early returns
   ReturnBBs.clear();
@@ -195,7 +192,7 @@ bool PadShortFunc::cyclesUntilReturn(MachineBasicBlock *MBB,
       return true;
     }
 
-    CyclesToEnd += TII->getInstrLatency(STI->getInstrItineraryData(), MI);
+    CyclesToEnd += TSM.computeInstrLatency(&MI);
   }
 
   VisitedBBs[MBB] = VisitedBBInfo(false, CyclesToEnd);
@@ -209,9 +206,8 @@ void PadShortFunc::addPadding(MachineBasicBlock *MBB,
                               MachineBasicBlock::iterator &MBBI,
                               unsigned int NOOPsToAdd) {
   DebugLoc DL = MBBI->getDebugLoc();
+  unsigned IssueWidth = TSM.getIssueWidth();
 
-  while (NOOPsToAdd-- > 0) {
-    BuildMI(*MBB, MBBI, DL, TII->get(X86::NOOP));
-    BuildMI(*MBB, MBBI, DL, TII->get(X86::NOOP));
-  }
+  for (unsigned i = 0, e = IssueWidth * NOOPsToAdd; i != e; ++i)
+    BuildMI(*MBB, MBBI, DL, TSM.getInstrInfo()->get(X86::NOOP));
 }