[InlineCost][TargetTransformInfo][AMDGPU] Consider cost of alloca instructions in the caller (1/2)

On AMDGPU, alloca instructions have penalty that can
be avoided when SROA is applied after inlining.

This patch introduces the default implementation of
TargetTransformInfo::getCallerAllocaCost.

Reviewed By: mtrofin

Differential Revision: https://reviews.llvm.org/D149740

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index d887adc..9ff277f 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -717,7 +717,9 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
   void onInitializeSROAArg(AllocaInst *Arg) override {
     assert(Arg != nullptr &&
            "Should not initialize SROA costs for null value.");
-    SROAArgCosts[Arg] = 0;
+    auto SROAArgCost = TTI.getCallerAllocaCost(&CandidateCall, Arg);
+    SROACostSavings += SROAArgCost;
+    SROAArgCosts[Arg] = SROAArgCost;
   }
 
   void onAggregateSROAUse(AllocaInst *SROAArg) override {
@@ -1191,7 +1193,12 @@ private:
               InstrCost);
   }
 
-  void onInitializeSROAArg(AllocaInst *Arg) override { SROACosts[Arg] = 0; }
+  void onInitializeSROAArg(AllocaInst *Arg) override {
+    auto SROAArgCost = TTI.getCallerAllocaCost(&CandidateCall, Arg);
+    SROACosts[Arg] = SROAArgCost;
+    SROACostSavingOpportunities += SROAArgCost;
+  }
+
   void onAggregateSROAUse(AllocaInst *Arg) override {
     SROACosts.find(Arg)->second += InstrCost;
     SROACostSavingOpportunities += InstrCost;