From 22eb80a11419825e13dee2ea34d9e4bf90dfd220 Mon Sep 17 00:00:00 2001
From: Easwaran Raman <eraman@google.com>
Date: Mon, 27 Jun 2016 22:31:53 +0000
Subject: [PATCH] Fix size computation of array allocation in inline cost
 analysis

Differential revision: http://reviews.llvm.org/D21690

llvm-svn: 273952
---
 llvm/lib/Analysis/InlineCost.cpp            |  7 ++--
 llvm/test/Transforms/Inline/array-alloca.ll | 36 +++++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 llvm/test/Transforms/Inline/array-alloca.ll

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 9382def00177..f6a9edae88d6 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -339,9 +339,10 @@ bool CallAnalyzer::visitAlloca(AllocaInst &I) {
   if (I.isArrayAllocation()) {
     Constant *Size = SimplifiedValues.lookup(I.getArraySize());
     if (auto *AllocSize = dyn_cast_or_null<ConstantInt>(Size)) {
+      const DataLayout &DL = F.getParent()->getDataLayout();
       Type *Ty = I.getAllocatedType();
-      // FIXME: This can't be right. AllocatedSize is in *bytes*.
-      AllocatedSize += Ty->getPrimitiveSizeInBits() * AllocSize->getZExtValue();
+      AllocatedSize = SaturatingMultiplyAdd(
+          AllocSize->getLimitedValue(), DL.getTypeAllocSize(Ty), AllocatedSize);
       return Base::visitAlloca(I);
     }
   }
@@ -350,7 +351,7 @@ bool CallAnalyzer::visitAlloca(AllocaInst &I) {
   if (I.isStaticAlloca()) {
     const DataLayout &DL = F.getParent()->getDataLayout();
     Type *Ty = I.getAllocatedType();
-    AllocatedSize += DL.getTypeAllocSize(Ty);
+    AllocatedSize = SaturatingAdd(DL.getTypeAllocSize(Ty), AllocatedSize);
   }
 
   // We will happily inline static alloca instructions.
diff --git a/llvm/test/Transforms/Inline/array-alloca.ll b/llvm/test/Transforms/Inline/array-alloca.ll
new file mode 100644
index 000000000000..57aecebd8baf
--- /dev/null
+++ b/llvm/test/Transforms/Inline/array-alloca.ll
@@ -0,0 +1,36 @@
+; RUN: opt -inline -S < %s | FileCheck %s
+%struct.A = type { i32 }
+
+define void @callee1(i32 %M) {
+entry:
+  %vla = alloca i32, i32 %M, align 16
+  ret void
+}
+
+define void @callee2(i32 %M) {
+entry:
+  %vla = alloca %struct.A, i32 %M, align 16
+  ret void
+}
+
+define void @callee3(i128 %M) {
+entry:
+  %vla = alloca i32, i128 %M, align 16
+  ret void
+}
+
+; CHECK-LABEL: @caller
+define void @caller() #0 {
+entry:
+  call void @caller()
+; CHECK-NOT: call void @callee1
+  call void @callee1(i32 256)
+; CHECK: call void @callee2
+  call void @callee2(i32 4096)
+; CHECK: call void @callee3
+; This is to test that there is no overflow in computing allocated size
+; call void @callee3(i128 0x8000000000000000);
+  call void @callee3(i128 9223372036854775808);
+  ret void
+}
+
-- 
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