From 7f094f7f9d3e3c529afcfd553cee3b64419e72f2 Mon Sep 17 00:00:00 2001
From: Kirill Naumov <knaumov@azul.com>
Date: Tue, 2 Jun 2020 18:57:30 +0000
Subject: [PATCH] [InlineCost] PrinterPass prints constants to which
 instructions are simplified

This patch enables printing of constants to see which instructions were
constant-folded. Needed for tests and better visiual analysis of
inliner's work.

Reviewers: apilipenko, mtrofin, davidxl, fedor.sergeev

Reviewed By: mtrofin

Differential Revision: https://reviews.llvm.org/D81024
---
 llvm/lib/Analysis/InlineCost.cpp             | 11 +++++++++++
 llvm/test/Transforms/Inline/simplified_to.ll | 15 +++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 llvm/test/Transforms/Inline/simplified_to.ll

diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 5054427..f69c7f3 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -402,6 +402,12 @@ public:
 
   InlineResult analyze();
 
+  Optional<Constant*> getSimplifiedValue(Instruction *I) {
+    if (SimplifiedValues.find(I) != SimplifiedValues.end())
+      return SimplifiedValues[I];
+    return None;
+  }
+
   // Keep a bunch of stats about the cost savings found so we can print them
   // out when debugging.
   unsigned NumConstantArgs = 0;
@@ -770,6 +776,11 @@ void InlineCostAnnotationWriter::emitInstructionAnnot(const Instruction *I,
     if (Record->hasThresholdChanged())
       OS << ", threshold delta = " << Record->getThresholdDelta();
   }
+  auto C = ICCA->getSimplifiedValue(const_cast<Instruction *>(I));
+  if (C) {
+    OS << ", simplified to ";
+    C.getValue()->print(OS, true);
+  }
   OS << "\n";
 }
 
diff --git a/llvm/test/Transforms/Inline/simplified_to.ll b/llvm/test/Transforms/Inline/simplified_to.ll
new file mode 100644
index 0000000..92c84b5
--- /dev/null
+++ b/llvm/test/Transforms/Inline/simplified_to.ll
@@ -0,0 +1,15 @@
+; RUN: opt < %s -passes="print<inline-cost>" 2>&1 | FileCheck %s
+
+; CHECK-LABEL: @test()
+; CHECK: cost before = {{.*}}, cost after = {{.*}}, threshold before = {{.*}}, threshold after = {{.*}}, cost delta = {{.*}}, simplified to i1 false
+; CHECK:   %1 = icmp eq i32 4, 5
+
+define i32 @test() {
+  %1 = icmp eq i32 4, 5
+  ret i32 0
+}
+
+define void @main() {
+  %1 = call i32 @test()
+  ret void
+}
-- 
2.7.4