[InlineCost] Introduce attributes to override InlineCost for inliner testing

[DaniilSuchkov]

Summary

This patch introduces four new string attributes: function-inline-cost, function-inline-threshold, call-inline-cost and call-threshold-bonus.
These attributes allow you to selectively override some aspects of InlineCost analysis. That would allow us to test inliner separately from the InlineCost analysis.

That could be useful when you're trying to write tests for inliner and you need to test some very specific situation, like "the inline cost has to be this high", or "the threshold has to be this low". Right now every time someone does that, they have get creative to come up with a way to make the InlineCost give them the number they need (like adding ~30 load/add pairs for a trivial test). This process can be somewhat tedious which can discourage some people from writing enough tests for their changes. Also, that results in tests that are fragile and can be easily broken without anyone noticing it because the test writer can't explicitly control what input the inliner will get from the inline cost analysis.

These new attributes will alleviate those problems to an extent.
I decided to make them string attributes because enum attributes seem to me way too invasive for such a narrow use-case.

[aeubanks]

this is a very nice feature :)

llvm/include/llvm/IR/InstrTypes.h

2282 ↗

(On Diff #369818)

I'd rather not change the semantics of getFnAttr, can this be in InlineCost instead?

llvm/lib/Analysis/InlineCost.cpp

138

making this a template seems unnecessary, just use int? that's what all the callers are using anyway

[DaniilSuchkov]

llvm/include/llvm/IR/InstrTypes.h

2282 ↗

(On Diff #369818)

This change makes getFnAttr's behavior similar to the one of hasFnAttr and hasRetAttr. Right now you can have a case when CB.getFnAttr(Attr).isValid() != CB.hasFnAttr(Attr) is true, which doesn't seem right, so I think that fixing it is better than creating a helper function that works around it.

However, I would agree that
a) what I described is a separate issue, definitely out of scope of this patch;
b) this change makes it way more likely that this patch will break something and will be reverted because of that
So a better decision is to add a workaround here, as you suggested, and then (maybe) fix this API inconsistency later in a separate patch.

llvm/lib/Analysis/InlineCost.cpp

138

Fair point.

[DaniilSuchkov]

Addressed the comments:

1. Got rid of CallBase::getFnAttr change, moved that part into a local helper function.
2. stringAttrAsInt isn't a template now.

[mtrofin]

lgtm, some nits

llvm/lib/Analysis/InlineCost.cpp

165

why not move stringAttrAsInt here? has no other callers, and getStringFnAttrAsInt is just calling it.

[DaniilSuchkov]

Merged stringAttrAsInt into getStringFnAttrAsInt.

llvm/lib/Analysis/InlineCost.cpp

 
 static cl::opt<bool> DisableGEPConstOperand(
     "disable-gep-const-evaluation", cl::Hidden, cl::init(false),
     cl::desc("Disables evaluation of GetElementPtr with constant operands"));
 
 namespace {
 class InlineCostCallAnalyzer;
 
+/// This function behaves more like CallBase::hasFnAttr: when it looks for the
+/// requested attribute, it check both the call instruction and the called
+/// function (if it's available and operand bundles don't prohibit that).
+Attribute getFnAttr(CallBase &CB, StringRef AttrKind) {
+  Attribute CallAttr = CB.getFnAttr(AttrKind);
+  if (CallAttr.isValid())
+    return CallAttr;
+
+  // Operand bundles override attributes on the called function, but don't
+  // override attributes directly present on the call instruction.
+  if (!CB.isFnAttrDisallowedByOpBundle(AttrKind))
+    if (const Function *F = CB.getCalledFunction())
+      return F->getFnAttribute(AttrKind);
+
+  return {};
+}
+
+Optional<int> getStringFnAttrAsInt(CallBase &CB, StringRef AttrKind) {
+  Attribute Attr = getFnAttr(CB, AttrKind);
+  int AttrValue;
+  if (Attr.getValueAsString().getAsInteger(10, AttrValue))
+    return None;
+  return AttrValue;
+}
+
 // This struct is used to store information about inline cost of a
 // particular instruction
 struct InstructionCostDetail {
   int CostBefore = 0;
   int CostAfter = 0;
   int ThresholdBefore = 0;
   int ThresholdAfter = 0;
 
   int getThresholdDelta() const { return ThresholdAfter - ThresholdBefore; }
 
   int getCostDelta() const { return CostAfter - CostBefore; }
protected:
   virtual InlineResult onAnalysisStart() { return InlineResult::success(); }
   /// Called if the analysis engine decides SROA cannot be done for the given
   /// alloca.
   virtual void onDisableSROA(AllocaInst *Arg) {}
 
   /// Called the analysis engine determines load elimination won't happen.
   virtual void onDisableLoadElimination() {}
 
+  /// Called when we visit a CallBase, before the analysis starts. Return false
+  /// to stop further processing of the instruction.
+  virtual bool onCallBaseVisitStart(CallBase &Call) { return true; }
+
   /// Called to account for a call.
   virtual void onCallPenalty() {}
 
   /// Called to account for the expectation the inlining would result in a load
   /// elimination.
   virtual void onLoadEliminationOpportunity() {}
 
   /// Called to account for the cost of argument setup for the Call in the
void onDisableSROA(AllocaInst *Arg) override {
     SROACostSavingsLost += CostIt->second;
     SROAArgCosts.erase(CostIt);
   }
 
   void onDisableLoadElimination() override {
     addCost(LoadEliminationCost);
     LoadEliminationCost = 0;
   }
+
+  bool onCallBaseVisitStart(CallBase &Call) override {
+    if (Optional<int> AttrCallThresholdBonus =
+            getStringFnAttrAsInt(Call, "call-threshold-bonus"))
+      Threshold += *AttrCallThresholdBonus;
+
+    if (Optional<int> AttrCallCost =
+            getStringFnAttrAsInt(Call, "call-inline-cost")) {
+      addCost(*AttrCallCost);
+      // Prevent further processing of the call since we want to override its
+      // inline cost, not just add to it.
+      return false;
+    }
+    return true;
+  }
+
   void onCallPenalty() override { addCost(CallPenalty); }
   void onCallArgumentSetup(const CallBase &Call) override {
     // Pay the price of the argument setup. We account for the average 1
     // instruction per call argument setup here.
     addCost(Call.arg_size() * InlineConstants::InstrCost);
   }
   void onLoadRelativeIntrinsic() override {
     // This is normally lowered to 4 LLVM instructions.
InlineResult finalizeAnalysis() override {
     // We applied the maximum possible vector bonus at the beginning. Now,
     // subtract the excess bonus, if any, from the Threshold before
     // comparing against Cost.
     if (NumVectorInstructions <= NumInstructions / 10)
       Threshold -= VectorBonus;
     else if (NumVectorInstructions <= NumInstructions / 2)
       Threshold -= VectorBonus / 2;
 
+    if (Optional<int> AttrCost =
+            getStringFnAttrAsInt(CandidateCall, "function-inline-cost"))
+      Cost = *AttrCost;
+
+    if (Optional<int> AttrThreshold =
+            getStringFnAttrAsInt(CandidateCall, "function-inline-threshold"))
+      Threshold = *AttrThreshold;
+
     if (auto Result = costBenefitAnalysis()) {
       DecidedByCostBenefit = true;
       if (Result.getValue())
         return InlineResult::success();
       else
         return InlineResult::failure("Cost over threshold.");
     }
 
if (Constant *C = ConstantFoldCall(&Call, F, ConstantArgs)) {
     SimplifiedValues[&Call] = C;
     return true;
   }
 
   return false;
 }
 
 bool CallAnalyzer::visitCallBase(CallBase &Call) {
+  if (!onCallBaseVisitStart(Call))
+    return true;
+
   if (Call.hasFnAttr(Attribute::ReturnsTwice) &&
       !F.hasFnAttribute(Attribute::ReturnsTwice)) {
     // This aborts the entire analysis.
     ExposesReturnsTwice = true;
     return false;
   }
   if (isa<CallInst>(Call) && cast<CallInst>(Call).cannotDuplicate())
     ContainsNoDuplicateCall = true;

llvm/test/Transforms/Inline/inline-call-penalty-option.ll

 ; Check that calls are not inlined if the call penalty is low. The value of the
 ; call penalty is provided with the '--inline-call-penalty' option.
 ;
 ; RUN: opt < %s -inline --inline-call-penalty=0 --inline-threshold=5 -S | FileCheck %s
 ; RUN: opt < %s -inline --inline-threshold=5 -S | FileCheck %s -check-prefix=DEFAULT_CALL_PENALTY
 
-define i32 @X9(i32 %x) nounwind {
-  %x2 = add i32 %x, %x
-  %x3 = add i32 %x2, %x
-  %x4 = add i32 %x3, %x
-  %x5 = add i32 %x4, %x
-  %x6 = add i32 %x5, %x
-  %x7 = add i32 %x6, %x
-  %x8 = add i32 %x7, %x
-  %x9 = add i32 %x8, %x
+declare void @extern()
 
-  ret i32 %x9
+define void @X9() nounwind {
+  call void @extern() "call-inline-cost"="30"
+  ret void
 }
 
-define i32 @f1(i32 %x) nounwind {
-  %res = call i32 @X9(i32 %x)
-  ret i32 %res
+define void @f1() nounwind {
+  call void @X9()
+  ret void
 ; CHECK-LABEL: @f1(
-; CHECK: %res = call i32 @X9
+; CHECK: call void @X9
 
 ; DEFAULT_CALL_PENALTY-LABEL: @f1(
-; DEFAULT_CALL_PENALTY-NOT: call
+; DEFAULT_CALL_PENALTY: call void @extern
+; DEFAULT_CALL_PENALTY-NOT: call void @X9
 }

llvm/test/Transforms/Inline/inline-cold-callee.ll

 ; RUN: opt < %s -inline -inlinecold-threshold=0 -S -enable-new-pm=0 | FileCheck %s
 
 ; This tests that a cold callee gets the (lower) inlinecold-threshold even without
 ; Cold hint and does not get inlined because the cost exceeds the inlinecold-threshold.
 ; A callee with identical body does gets inlined because cost fits within the
 ; inline-threshold
 
 define i32 @callee1(i32 %x) !prof !21 {
   %x1 = add i32 %x, 1
-  %x2 = add i32 %x1, 1
-  %x3 = add i32 %x2, 1
-  call void @extern()
-  ret i32 %x3
+  ret i32 %x1
 }
 
 define i32 @callee2(i32 %x) !prof !22 {
 ; CHECK-LABEL: @callee2(
   %x1 = add i32 %x, 1
-  %x2 = add i32 %x1, 1
-  %x3 = add i32 %x2, 1
-  call void @extern()
-  ret i32 %x3
+  ret i32 %x1
 }
 
 define i32 @caller2(i32 %y1) !prof !22 {
 ; CHECK-LABEL: @caller2(
 ; CHECK: call i32 @callee2
 ; CHECK-NOT: call i32 @callee1
-; CHECK: ret i32 %x3.i
-  %y2 = call i32 @callee2(i32 %y1)
-  %y3 = call i32 @callee1(i32 %y2)
+; CHECK: ret i32 %x1.i
+  %y2 = call i32 @callee2(i32 %y1) "function-inline-cost"="10"
+  %y3 = call i32 @callee1(i32 %y2) "function-inline-cost"="10"
   ret i32 %y3
 }
 
-declare void @extern()
-
 !llvm.module.flags = !{!1}
 !21 = !{!"function_entry_count", i64 100}
 !22 = !{!"function_entry_count", i64 1}
 
 !1 = !{i32 1, !"ProfileSummary", !2}
 !2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
 !3 = !{!"ProfileFormat", !"InstrProf"}
 !4 = !{!"TotalCount", i64 10000}

llvm/test/Transforms/Inline/inline-cold-callsite-pgo.ll

 ; RUN: opt < %s -passes='require<profile-summary>,cgscc(inline)' -inline-threshold=100 -inline-cold-callsite-threshold=0 -S | FileCheck %s
 
 ; This tests that a cold callsite gets the inline-cold-callsite-threshold
 ; and does not get inlined. Another callsite to an identical callee that
 ; is not cold gets inlined because cost is below the inline-threshold.
 
-define i32 @callee1(i32 %x) !prof !21 {
+define i32 @callee1(i32 %x) "function-inline-cost"="30" !prof !21 {
   %x1 = add i32 %x, 1
-  %x2 = add i32 %x1, 1
-  %x3 = add i32 %x2, 1
   call void @extern()
-  ret i32 %x3
+  ret i32 %x1
 }
 
 define i32 @caller(i32 %n) !prof !22 {
 ; CHECK-LABEL: @caller(
   %cond = icmp sle i32 %n, 100
   br i1 %cond, label %cond_true, label %cond_false, !prof !0
 
 cond_true:
 ; CHECK-LABEL: cond_true:
 ; CHECK-NOT: call i32 @callee1
-; CHECK: ret i32 %x3.i
+; CHECK: ret i32 %x1.i
   %i = call i32 @callee1(i32 %n)
   ret i32 %i
 cond_false:
 ; CHECK-LABEL: cond_false:
 ; CHECK: call i32 @callee1
 ; CHECK: ret i32 %j
   %j = call i32 @callee1(i32 %n)
   ret i32 %j

llvm/test/Transforms/Inline/inline-cold-callsite.ll

 
 ; RUN: opt < %s -passes='require<profile-summary>,cgscc(inline)' -inline-threshold=100 -inline-cold-callsite-threshold=0 -S | FileCheck %s
 
 ; This tests that a cold callsite gets the inline-cold-callsite-threshold
 ; and does not get inlined. Another callsite to an identical callee that
 ; is not cold gets inlined because cost is below the inline-threshold.
 
-define void @callee() {
-  call void @extern()
+define void @callee() "function-inline-cost"="10" {
   call void @extern()
   ret void
 }
 
 declare void @extern()
 declare i1 @ext(i32)
 
 ; CHECK-LABEL: caller

llvm/test/Transforms/Inline/inline-cold.ll

 ; RUN: opt < %s -passes='require<profile-summary>,cgscc(inline)' -S | FileCheck %s -check-prefix=DEFAULT
 ; The same cold function will not be inlined with the default behavior.
 
 @a = global i32 4
 
 ; This function should be larger than the cold threshold (75), but smaller
 ; than the regular threshold.
 ; Function Attrs: nounwind readnone uwtable
-define i32 @simpleFunction(i32 %a) #0 {
+define i32 @simpleFunction(i32 %a) #0 "function-inline-cost"="80" {
 entry:
-  call void @extern()
-  %a1 = load volatile i32, i32* @a
-  %x1 = add i32 %a1,  %a1
-  %a2 = load volatile i32, i32* @a
-  %x2 = add i32 %x1, %a2
-  %a3 = load volatile i32, i32* @a
-  %x3 = add i32 %x2, %a3
-  %a4 = load volatile i32, i32* @a
-  %x4 = add i32 %x3, %a4
-  %a5 = load volatile i32, i32* @a
-  %x5 = add i32 %x4, %a5
-  %a6 = load volatile i32, i32* @a
-  %x6 = add i32 %x5, %a6
-  %a7 = load volatile i32, i32* @a
-  %x7 = add i32 %x6, %a6
-  %a8 = load volatile i32, i32* @a
-  %x8 = add i32 %x7, %a8
-  %a9 = load volatile i32, i32* @a
-  %x9 = add i32 %x8, %a9
-  %a10 = load volatile i32, i32* @a
-  %x10 = add i32 %x9, %a10
-  %a11 = load volatile i32, i32* @a
-  %x11 = add i32 %x10, %a11
-  %a12 = load volatile i32, i32* @a
-  %x12 = add i32 %x11, %a12
-  %add = add i32 %x12, %a
-  ret i32 %add
+  ret i32 %a
 }
 
 ; Function Attrs: nounwind cold readnone uwtable
-define i32 @ColdFunction(i32 %a) #1 {
+define i32 @ColdFunction(i32 %a) #1 "function-inline-cost"="30" {
 ; CHECK-LABEL: @ColdFunction
 ; CHECK: ret
 ; OVERRIDE-LABEL: @ColdFunction
 ; OVERRIDE: ret
 ; DEFAULT-LABEL: @ColdFunction
 ; DEFAULT: ret
 entry:
-  call void @extern()
-  %a1 = load volatile i32, i32* @a
-  %x1 = add i32 %a1,  %a1
-  %a2 = load volatile i32, i32* @a
-  %x2 = add i32 %x1, %a2
-  %a3 = load volatile i32, i32* @a
-  %x3 = add i32 %x2, %a3
-  %a4 = load volatile i32, i32* @a
-  %x4 = add i32 %x3, %a4
-  %add = add i32 %x4, %a
-  ret i32 %add
+  ret i32 %a
 }
 
 ; This function should be larger than the default cold threshold (225).
-define i32 @ColdFunction2(i32 %a) #1 {
+define i32 @ColdFunction2(i32 %a) #1 "function-inline-cost"="250" {
 ; CHECK-LABEL: @ColdFunction2
 ; CHECK: ret
 ; OVERRIDE-LABEL: @ColdFunction2
 ; OVERRIDE: ret
 ; DEFAULT-LABEL: @ColdFunction2
 ; DEFAULT: ret
 entry:
-  call void @extern()
-  %a1 = load volatile i32, i32* @a
-  %x1 = add i32 %a1,  %a1
-  %a2 = load volatile i32, i32* @a
-  %x2 = add i32 %x1, %a2
-  %a3 = load volatile i32, i32* @a
-  %x3 = add i32 %x2, %a3
-  %a4 = load volatile i32, i32* @a
-  %x4 = add i32 %x3, %a4
-  %a5 = load volatile i32, i32* @a
-  %x5 = add i32 %x4, %a5
-  %a6 = load volatile i32, i32* @a
-  %x6 = add i32 %x5, %a6
-  %a7 = load volatile i32, i32* @a
-  %x7 = add i32 %x6, %a7
-  %a8 = load volatile i32, i32* @a
-  %x8 = add i32 %x7, %a8
-  %a9 = load volatile i32, i32* @a
-  %x9 = add i32 %x8, %a9
-  %a10 = load volatile i32, i32* @a
-  %x10 = add i32 %x9, %a10
-  %a11 = load volatile i32, i32* @a
-  %x11 = add i32 %x10, %a11
-  %a12 = load volatile i32, i32* @a
-  %x12 = add i32 %x11, %a12
-
-  %a21 = load volatile i32, i32* @a
-  %x21 = add i32 %x12, %a21
-  %a22 = load volatile i32, i32* @a
-  %x22 = add i32 %x21, %a22
-  %a23 = load volatile i32, i32* @a
-  %x23 = add i32 %x22, %a23
-  %a24 = load volatile i32, i32* @a
-  %x24 = add i32 %x23, %a24
-  %a25 = load volatile i32, i32* @a
-  %x25 = add i32 %x24, %a25
-  %a26 = load volatile i32, i32* @a
-  %x26 = add i32 %x25, %a26
-  %a27 = load volatile i32, i32* @a
-  %x27 = add i32 %x26, %a27
-  %a28 = load volatile i32, i32* @a
-  %x28 = add i32 %x27, %a28
-  %a29 = load volatile i32, i32* @a
-  %x29 = add i32 %x28, %a29
-  %a30 = load volatile i32, i32* @a
-  %x30 = add i32 %x29, %a30
-  %a31 = load volatile i32, i32* @a
-  %x31 = add i32 %x30, %a31
-  %a32 = load volatile i32, i32* @a
-  %x32 = add i32 %x31, %a32
-
-  %a41 = load volatile i32, i32* @a
-  %x41 = add i32 %x32, %a41
-  %a42 = load volatile i32, i32* @a
-  %x42 = add i32 %x41, %a42
-  %a43 = load volatile i32, i32* @a
-  %x43 = add i32 %x42, %a43
-  %a44 = load volatile i32, i32* @a
-  %x44 = add i32 %x43, %a44
-  %a45 = load volatile i32, i32* @a
-  %x45 = add i32 %x44, %a45
-  %a46 = load volatile i32, i32* @a
-  %x46 = add i32 %x45, %a46
-  %a47 = load volatile i32, i32* @a
-  %x47 = add i32 %x46, %a47
-  %a48 = load volatile i32, i32* @a
-  %x48 = add i32 %x47, %a48
-  %a49 = load volatile i32, i32* @a
-  %x49 = add i32 %x48, %a49
-  %a50 = load volatile i32, i32* @a
-  %x50 = add i32 %x49, %a50
-  %a51 = load volatile i32, i32* @a
-  %x51 = add i32 %x50, %a51
-  %a52 = load volatile i32, i32* @a
-  %x52 = add i32 %x51, %a52
-
-  %add = add i32 %x52, %a
-  ret i32 %add
+  ret i32 %a
 }
 
 ; Function Attrs: nounwind readnone uwtable
 define i32 @bar(i32 %a) #0 {
 ; CHECK-LABEL: @bar
 ; CHECK: call i32 @ColdFunction(i32 5)
 ; CHECK-NOT: call i32 @simpleFunction(i32 6)
 ; CHECK: call i32 @ColdFunction2(i32 5)

llvm/test/Transforms/Inline/inline-cost-attributes.ll

+; REQUIRES: asserts
+; RUN: opt -inline-cost-full -passes='cgscc(inline)' -debug-only=inline -disable-output %s 2>&1 | FileCheck --check-prefix=INLINER %s
+; RUN: opt -inline-cost-full -passes='print<inline-cost>' -disable-output %s 2>&1 | FileCheck --check-prefix=COST %s
+
+declare void @extern() "call-threshold-bonus"="31"
+
+define void @fn1() "function-inline-cost"="321" "function-inline-threshold"="123" "call-inline-cost"="271" {
+entry:
+  ret void
+}
+
+define void @fn2() "function-inline-threshold"="41" {
+; INLINER-LABEL: Inlining calls in: fn2
+; INLINER-NEXT: Function size: 6
+; INLINER-NEXT: NOT Inlining (cost=321, threshold=123), Call:   call void @fn1()
+; INLINER-NEXT: NOT Inlining (cost=321, threshold=321), Call:   call void @fn1()
+; INLINER-NEXT: NOT Inlining (cost=197, threshold=123), Call:   call void @fn1()
+; INLINER-NEXT: Inlining (cost=197, threshold=321), Call:   call void @fn1()
+
+; COST-LABEL: define void @fn2()
+; COST-NEXT: entry:
+; COST-NEXT: threshold delta = 31
+; COST-NEXT: call void @extern()
+; COST-NEXT: cost delta = 132, threshold delta = 193
+; COST-NEXT: call void @fn1()
+; COST-NEXT: cost delta = 0
+; COST-NEXT: call void @fn1()
+; COST-NEXT: cost delta = 271, threshold delta = 17
+; COST-NEXT: call void @fn1()
+; COST-NEXT: cost delta = 473
+; COST-NEXT: call void @fn1()
+
+entry:
+  call void @extern()
+  call void @fn1() "call-inline-cost"="132" "call-threshold-bonus"="193"
+  call void @fn1() "call-inline-cost"="0" "function-inline-threshold"="321"
+  call void @fn1() "call-threshold-bonus"="17" "function-inline-cost"="197"
+  call void @fn1() "call-inline-cost"="473" "function-inline-cost"="197" "function-inline-threshold"="321"
+  ret void
+}
+
+define void @fn3() {
+; INLINER-LABEL: Inlining calls in: fn3
+; INLINER-NEXT: Function size: 3
+; INLINER-NEXT: Inlining (cost=386, threshold=849), Call:   call void @fn1()
+; INLINER-NEXT: Size after inlining: 2
+; INLINER-NEXT: NOT Inlining (cost=403, threshold=41), Call:   call void @fn2()
+
+entry:
+  call void @fn1() "function-inline-cost"="386" "function-inline-threshold"="849"
+  call void @fn2()
+  ret void
+}

llvm/test/Transforms/Inline/inline-threshold.ll

 ; Test that -inline-threshold overrides thresholds derived from opt levels.
 ; RUN: opt < %s -O2 -inline-threshold=500 -S  | FileCheck %s
 ; RUN: opt < %s -O3 -inline-threshold=500 -S  | FileCheck %s
 ; RUN: opt < %s -Os -inline-threshold=500 -S  | FileCheck %s
 ; RUN: opt < %s -Oz -inline-threshold=500 -S  | FileCheck %s
 
 @a = global i32 4
 
 define i32 @simpleFunction(i32 %a) #0 {
 entry:
   %a1 = load volatile i32, i32* @a
-  %x1 = add i32 %a1,  %a1
-  %cmp = icmp eq i32 %a1, 0
-  br i1 %cmp, label %if.then, label %if.else
-if.then:
-  %a2 = load volatile i32, i32* @a
-  %x2_0 = add i32 %x1, %a2
-  br label %if.else
-if.else:
-  %x2 = phi i32 [ %x1, %entry ], [ %x2_0, %if.then ]
-  %a3 = load volatile i32, i32* @a
-  %x3 = add i32 %x2, %a3
-  %a4 = load volatile i32, i32* @a
-  %x4 = add i32 %x3, %a4
-  %a5 = load volatile i32, i32* @a
-  %x5 = add i32 %x4, %a5
-  %a6 = load volatile i32, i32* @a
-  %x6 = add i32 %x5, %a6
-  %a7 = load volatile i32, i32* @a
-  %x7 = add i32 %x6, %a7
-  %a8 = load volatile i32, i32* @a
-  %x8 = add i32 %x7, %a8
-  %a9 = load volatile i32, i32* @a
-  %x9 = add i32 %x8, %a9
-  %a10 = load volatile i32, i32* @a
-  %x10 = add i32 %x9, %a10
-  %a11 = load volatile i32, i32* @a
-  %x11 = add i32 %x10, %a11
-  %a12 = load volatile i32, i32* @a
-  %x12 = add i32 %x11, %a12
-  %a13 = load volatile i32, i32* @a
-  %x13 = add i32 %x12, %a13
-  %a14 = load volatile i32, i32* @a
-  %x14 = add i32 %x13, %a14
-  %a15 = load volatile i32, i32* @a
-  %x15 = add i32 %x14, %a15
-  %a16 = load volatile i32, i32* @a
-  %x16 = add i32 %x15, %a16
-  %a17 = load volatile i32, i32* @a
-  %x17 = add i32 %x16, %a17
-  %a18 = load volatile i32, i32* @a
-  %x18 = add i32 %x17, %a18
-  %a19 = load volatile i32, i32* @a
-  %x19 = add i32 %x18, %a19
-  %a20 = load volatile i32, i32* @a
-  %x20 = add i32 %x19, %a20
-  %a21 = load volatile i32, i32* @a
-  %x21 = add i32 %x20, %a21
-  %a22 = load volatile i32, i32* @a
-  %x22 = add i32 %x21, %a22
-  %a23 = load volatile i32, i32* @a
-  %x23 = add i32 %x22, %a23
-  %a24 = load volatile i32, i32* @a
-  %x24 = add i32 %x23, %a24
-  %a25 = load volatile i32, i32* @a
-  %x25 = add i32 %x24, %a25
-  %a26 = load volatile i32, i32* @a
-  %x26 = add i32 %x25, %a26
-  %a27 = load volatile i32, i32* @a
-  %x27 = add i32 %x26, %a27
-  %a28 = load volatile i32, i32* @a
-  %x28 = add i32 %x27, %a28
-  %a29 = load volatile i32, i32* @a
-  %x29 = add i32 %x28, %a29
-  %add = add i32 %x29, %a
-  ret i32 %add
+  %x1 = add i32 %a1,  %a
+  ret i32 %x1
 }
 
 ; Function Attrs: nounwind readnone uwtable
 define i32 @bar(i32 %a) #0 {
 ; CHECK-LABEL: @bar
-; CHECK-NOT: call i32 @simpleFunction(i32 6)
+; CHECK: load volatile
+; CHECK-NEXT: add i32
+; CHECK-NEXT: call i32 @simpleFunction
 ; CHECK: ret
 entry:
-  %i = tail call i32 @simpleFunction(i32 6)
-  ret i32 %i
+  %i = tail call i32 @simpleFunction(i32 6) "function-inline-cost"="749"
+  %j = tail call i32 @simpleFunction(i32 %i) "function-inline-cost"="750"
+  ret i32 %j
 }
 
 attributes #0 = { nounwind readnone uwtable }