From 1c9ca7d101354e5478ef064e52c8ca174bd80aa0 Mon Sep 17 00:00:00 2001
From: Diego Trevino Ferrer <diegof30@gmail.com>
Date: Wed, 7 Aug 2019 00:42:50 +0000
Subject: [Bugpoint redesign] Added Pass to Remove Global Variables

Summary:
This pass tries to remove Global Variables, as well as their derived uses. For example if a variable `@x` is used by `%call1` and `%call2`, both these uses and the definition of `@x` are deleted. Moreover if `%call1` or `%call2` are used elsewhere those uses are also deleted, and so on recursively.

I'm still uncertain if this pass should remove derived uses, I'm open to suggestions.

Subscribers: mgorny, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64176

llvm-svn: 368115
---
 llvm/test/Reduce/Inputs/remove-global-vars.sh |  9 +++++++
 llvm/test/Reduce/remove-global-vars.ll        | 38 +++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)
 create mode 100755 llvm/test/Reduce/Inputs/remove-global-vars.sh
 create mode 100644 llvm/test/Reduce/remove-global-vars.ll

(limited to 'llvm/test/Reduce')

diff --git a/llvm/test/Reduce/Inputs/remove-global-vars.sh b/llvm/test/Reduce/Inputs/remove-global-vars.sh
new file mode 100755
index 00000000000..cb656878cd9
--- /dev/null
+++ b/llvm/test/Reduce/Inputs/remove-global-vars.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+matches=$(cat $1 | grep "@interesting = global" | wc -l)
+
+if [[ $matches > 0 ]]; then
+  exit 0
+else
+  exit 1
+fi
diff --git a/llvm/test/Reduce/remove-global-vars.ll b/llvm/test/Reduce/remove-global-vars.ll
new file mode 100644
index 00000000000..7acd35fd612
--- /dev/null
+++ b/llvm/test/Reduce/remove-global-vars.ll
@@ -0,0 +1,38 @@
+; Test that llvm-reduce can remove uninteresting Global Variables as well as
+; their direct uses.
+;
+; RUN: llvm-reduce --test %p/Inputs/remove-global-vars.sh %s
+; RUN: cat reduced.ll | FileCheck %s
+; REQUIRES: plugins, shell
+
+@uninteresting1 = global i32 0, align 4
+; CHECK: @interesting = global
+@interesting = global i32 5, align 4
+; CHECK-NOT: global
+@uninteresting2 = global i32 25, align 4
+@uninteresting3 = global i32 50, align 4
+
+define i32 @main() {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  ; CHECK-NOT: load i32, i32* @uninteresting2, align 4
+  %0 = load i32, i32* @uninteresting2, align 4
+  store i32 %0, i32* @interesting, align 4
+  ; CHECK-NOT: load i32, i32* @uninteresting3, align 4
+  %1 = load i32, i32* @uninteresting3, align 4
+  %dec = add nsw i32 %1, -1
+  ; CHECK-NOT: store i32 %dec, i32* @uninteresting3, align 4
+  store i32 %dec, i32* @uninteresting3, align 4
+  ; CHECK: load i32, i32* @interesting, align 4
+  %2 = load i32, i32* @interesting, align 4
+  ; CHECK-NOT: load i32, i32* @uninteresting2, align 4
+  %3 = load i32, i32* @uninteresting2, align 4
+  %add = add nsw i32 %2, %3
+  ; CHECK-NOT: store i32 %add, i32* @uninteresting1, align 4
+  store i32 %add, i32* @uninteresting1, align 4
+  store i32 10, i32* @interesting, align 4
+  ; CHECK: load i32, i32* @interesting, align 4
+  %4 = load i32, i32* @interesting, align 4
+  ret i32 0
+}
-- 
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