From bb578ef0dd7eebacebfb03a2e7bdfb3e3ba26b7e Mon Sep 17 00:00:00 2001
From: Easwaran Raman <eraman@google.com>
Date: Thu, 19 May 2016 23:02:09 +0000
Subject: [PATCH] Allow -inline-threshold to override default threshold.

Before r257832, the threshold used by SimpleInliner was explicitly specified or generated from opt levels and passed to the base class Inliner's constructor. There, it was first overridden by explicitly specified -inline-threshold. The refactoring in r257832 did not preserve this behavior for all opt levels. This change brings back the original behavior.

Differential Revision: http://reviews.llvm.org/D20452

llvm-svn: 270153
---
 llvm/lib/Analysis/InlineCost.cpp              | 11 ++-
 .../Transforms/Inline/inline-threshold.ll     | 89 +++++++++++++++++++
 2 files changed, 96 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/Transforms/Inline/inline-threshold.ll

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index d3b2930d7eab..549d3a97ec0a 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -612,11 +612,14 @@ void CallAnalyzer::updateThreshold(CallSite CS, Function &Callee) {
     return;
   }
 
-  // If -inline-threshold is not given, listen to the optsize and minsize
-  // attributes when they would decrease the threshold.
   Function *Caller = CS.getCaller();
-
-  if (!(DefaultInlineThreshold.getNumOccurrences() > 0)) {
+  if (DefaultInlineThreshold.getNumOccurrences() > 0) {
+    // Explicitly specified -inline-threhold overrides the threshold passed to
+    // CallAnalyzer's constructor.
+    Threshold = DefaultInlineThreshold;
+  } else {
+    // If -inline-threshold is not given, listen to the optsize and minsize
+    // attributes when they would decrease the threshold.
     if (Caller->optForMinSize() && OptMinSizeThreshold < Threshold)
       Threshold = OptMinSizeThreshold;
     else if (Caller->optForSize() && OptSizeThreshold < Threshold)
diff --git a/llvm/test/Transforms/Inline/inline-threshold.ll b/llvm/test/Transforms/Inline/inline-threshold.ll
new file mode 100644
index 000000000000..cb0c8e9fcc44
--- /dev/null
+++ b/llvm/test/Transforms/Inline/inline-threshold.ll
@@ -0,0 +1,89 @@
+; 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
+}
+
+; Function Attrs: nounwind readnone uwtable
+define i32 @bar(i32 %a) #0 {
+; CHECK-LABEL: @bar
+; CHECK-NOT: call i32 @simpleFunction(i32 6)
+; CHECK: ret
+entry:
+  %i = tail call i32 @simpleFunction(i32 6)
+  ret i32 %i
+}
+
+attributes #0 = { nounwind readnone uwtable }