From 9a764dfa92ba7a8a64472410817459b00a8b003a Mon Sep 17 00:00:00 2001
From: Eric Christopher <echristo@gmail.com>
Date: Mon, 7 Apr 2014 13:36:21 +0000
Subject: [PATCH] Handle vlas during inline cost computation if they'll be
 turned into a constant size alloca by inlining.

Ran a run over the testsuite, no results out of the noise, fixes
the testcase in the PR.

PR19115.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205710 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/IPA/InlineCost.cpp      | 11 +++++++-
 test/Transforms/Inline/inline-vla.ll | 38 ++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/Inline/inline-vla.ll

diff --git a/lib/Analysis/IPA/InlineCost.cpp b/lib/Analysis/IPA/InlineCost.cpp
index 8dafc1c1c61..a803f8c3bf9 100644
--- a/lib/Analysis/IPA/InlineCost.cpp
+++ b/lib/Analysis/IPA/InlineCost.cpp
@@ -287,8 +287,17 @@ bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
 }
 
 bool CallAnalyzer::visitAlloca(AllocaInst &I) {
-  // FIXME: Check whether inlining will turn a dynamic alloca into a static
+  // Check whether inlining will turn a dynamic alloca into a static
   // alloca, and handle that case.
+  if (I.isArrayAllocation()) {
+    if (Constant *Size = SimplifiedValues.lookup(I.getArraySize())) {
+      ConstantInt *AllocSize = dyn_cast<ConstantInt>(Size);
+      assert(AllocSize && "Allocation size not a constant int?");
+      Type *Ty = I.getAllocatedType();
+      AllocatedSize += Ty->getPrimitiveSizeInBits() * AllocSize->getZExtValue();
+      return Base::visitAlloca(I);
+    }
+  }
 
   // Accumulate the allocated size.
   if (I.isStaticAlloca()) {
diff --git a/test/Transforms/Inline/inline-vla.ll b/test/Transforms/Inline/inline-vla.ll
new file mode 100644
index 00000000000..dc9deaafe74
--- /dev/null
+++ b/test/Transforms/Inline/inline-vla.ll
@@ -0,0 +1,38 @@
+; RUN: opt -S -inline %s -o - | FileCheck %s
+
+; Check that memcpy2 is completely inlined away.
+; CHECK-NOT: memcpy2
+
+@.str = private unnamed_addr constant [2 x i8] c"a\00", align 1
+@.str1 = private unnamed_addr constant [3 x i8] c"ab\00", align 1
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @main(i32 %argc, i8** nocapture readnone %argv) #0 {
+entry:
+  %data = alloca [2 x i8], align 1
+  %arraydecay = getelementptr inbounds [2 x i8]* %data, i64 0, i64 0
+  call fastcc void @memcpy2(i8* %arraydecay, i8* getelementptr inbounds ([2 x i8]* @.str, i64 0, i64 0), i64 1)
+  call fastcc void @memcpy2(i8* %arraydecay, i8* getelementptr inbounds ([3 x i8]* @.str1, i64 0, i64 0), i64 2)
+  ret i32 0
+}
+
+; Function Attrs: inlinehint nounwind ssp uwtable
+define internal fastcc void @memcpy2(i8* nocapture %dst, i8* nocapture readonly %src, i64 %size) #1 {
+entry:
+  %vla = alloca i64, i64 %size, align 16
+  %0 = bitcast i64* %vla to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %src, i64 %size, i32 1, i1 false)
+  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %0, i64 %size, i32 1, i1 false)
+  ret void
+}
+
+; Function Attrs: nounwind
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #2
+
+attributes #0 = { nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { inlinehint nounwind ssp uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #2 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = metadata !{metadata !"clang version 3.5.0 (trunk 205695) (llvm/trunk 205706)"}
-- 
2.34.1