[Inliner] Assert that the computed inline threshold is non-negative.

[chandlerc]

LGTM, thanks for pinning this down.

lib/Analysis/InlineCost.cpp

InlineResult CallAnalyzer::analyzeCall(CallSite CS) {
   // FIXME: It would be nice to remove all such bonuses. At least it would be
   // nice to base the bonus values on something more scientific.
   assert(NumInstructions == 0);
   assert(NumVectorInstructions == 0);
 
   // Update the threshold based on callsite properties
   updateThreshold(CS, F);
 
+  // While Threshold depends on commandline options that can take negative
+  // values, we want to enforce the invariant that the computed threshold and
+  // bonuses are non-negative.
+  assert(Threshold >= 0);
+  assert(SingleBBBonus >= 0);
+  assert(VectorBonus >= 0);
+
   // Speculatively apply all possible bonuses to Threshold. If cost exceeds
   // this Threshold any time, and cost cannot decrease, we can stop processing
   // the rest of the function body.
   Threshold += (SingleBBBonus + VectorBonus);
 
   // Give out bonuses for the callsite, as the instructions setting them up
   // will be gone after inlining.
   Cost -= getCallsiteCost(CS, DL);

test/Transforms/Inline/inline-remark.ll

-; RUN: opt < %s -inline -inline-remark-attribute --inline-threshold=-2 -S | FileCheck %s
+; RUN: opt < %s -inline -inline-remark-attribute --inline-threshold=0 -S | FileCheck %s
 
 ; Test that the inliner adds inline remark attributes to non-inlined callsites.
 
+declare void @ext();
+
 define void @foo() {
   call void @bar(i1 true)
   ret void
 }
 
 define void @bar(i1 %p) {
   br i1 %p, label %bb1, label %bb2
 
 bb1:
   call void @foo()
+  call void @ext()
   ret void
 
 bb2:
   call void @bar(i1 true)
   ret void
 }
 
 ;; Test 1 - Add different inline remarks to similar callsites.

 ; CHECK-LABEL: @test2
 ; CHECK-NEXT: call void @noop() [[ATTR3:#[0-9]+]] [ "CUSTOM_OPERAND_BUNDLE"() ]
 ; CHECK-NEXT: ret void
   call void @noop() ; extepected to be inlined
   call void @noop() [ "CUSTOM_OPERAND_BUNDLE"() ] ; cannot be inlined because of unsupported operand bundle
   ret void
 }
 
-; CHECK: attributes [[ATTR1]] = { "inline-remark"="(cost=-5, threshold=-6)" }
+; CHECK: attributes [[ATTR1]] = { "inline-remark"="(cost=25, threshold=0)" }
 ; CHECK: attributes [[ATTR2]] = { "inline-remark"="(cost=never): recursive" }
 ; CHECK: attributes [[ATTR3]] = { "inline-remark"="unsupported operand bundle; (cost={{.*}}, threshold={{.*}})" }