[PATCH] D35850: [InlineCost] Add cl::opt to allow full inline cost to be computed for debugging purposes.

[Chad Rosier via Phabricator via llvm-commits]

mcrosier created this revision.

Currently, the inline cost model will bail once the inline cost exceeds the inline threshold in order to avoid unnecessary compile-time.  However, when debugging I found it useful to compute the full cost, so I added this command line option to override the default behavior.

I wanted to see if others thought this might be useful.  I also wanted to have someone more familiar with the inline cost model double check to make sure the patch is correct.

Chad


https://reviews.llvm.org/D35850

Files:
  lib/Analysis/InlineCost.cpp


Index: lib/Analysis/InlineCost.cpp
===================================================================
--- lib/Analysis/InlineCost.cpp
+++ lib/Analysis/InlineCost.cpp
@@ -72,6 +72,11 @@
              "entry frequency, for a callsite to be cold in the absence of "
              "profile information."));
 
+static cl::opt<bool> ComputeFullInlineCost(
+    "inline-cost-full", cl::Hidden, cl::init(false),
+    cl::desc("Compute the full inline cost of a call site even when the cost "
+             "exceeds the threshold."));
+
 namespace {
 
 class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
@@ -1225,7 +1230,7 @@
 
     // Check if we've past the maximum possible threshold so we don't spin in
     // huge basic blocks that will never inline.
-    if (Cost > Threshold)
+    if (Cost > Threshold && !ComputeFullInlineCost)
       return false;
   }
 
@@ -1327,7 +1332,7 @@
     Cost += InlineConstants::ColdccPenalty;
 
   // Check if we're done. This can happen due to bonuses and penalties.
-  if (Cost > Threshold)
+  if (Cost > Threshold && !ComputeFullInlineCost)
     return false;
 
   if (F.empty())
@@ -1392,7 +1397,7 @@
   for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
     // Bail out the moment we cross the threshold. This means we'll under-count
     // the cost, but only when undercounting doesn't matter.
-    if (Cost > Threshold)
+    if (Cost > Threshold && !ComputeFullInlineCost)
       break;
 
     BasicBlock *BB = BBWorklist[Idx];
@@ -1558,13 +1563,14 @@
     return llvm::InlineCost::getNever();
   }
 
+  Function *Caller = CS.getCaller();
   // Never inline functions with conflicting attributes (unless callee has
   // always-inline attribute).
-  if (!functionsHaveCompatibleAttributes(CS.getCaller(), Callee, CalleeTTI))
+  if (!functionsHaveCompatibleAttributes(Caller, Callee, CalleeTTI))
     return llvm::InlineCost::getNever();
 
   // Don't inline this call if the caller has the optnone attribute.
-  if (CS.getCaller()->hasFnAttribute(Attribute::OptimizeNone))
+  if (Caller->hasFnAttribute(Attribute::OptimizeNone))
     return llvm::InlineCost::getNever();
 
   // Don't inline functions which can be interposed at link-time.  Don't inline
@@ -1576,7 +1582,7 @@
     return llvm::InlineCost::getNever();
 
   DEBUG(llvm::dbgs() << "      Analyzing call of " << Callee->getName()
-                     << "...\n");
+                     << "... (Caller:" << Caller->getName() << ")\n");
 
   CallAnalyzer CA(CalleeTTI, GetAssumptionCache, GetBFI, PSI, *Callee, CS,
                   Params);


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