linux-kernel - [PATCH] coccinelle: Add a script to find and remove unnecessary ifs with no body

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Message-ID: <20131102143236.GA18084@leaf>
Date:	Sat, 2 Nov 2013 07:32:37 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	Julia Lawall <Julia.Lawall@...6.fr>,
	Gilles Muller <Gilles.Muller@...6.fr>,
	Nicolas Palix <nicolas.palix@...g.fr>,
	Michal Marek <mmarek@...e.cz>, linux-kernel@...r.kernel.org,
	cocci@...teme.lip6.fr
Subject: [PATCH] coccinelle: Add a script to find and remove unnecessary ifs
 with no body

This script matches code like:

if (foo) {}

and either eliminates it (if foo has no side effects) or replaces it
with foo (if foo has side effects).

Works perfectly in report mode; the results of patch mode are
semantically correct but may still benefit from further simplification.

Signed-off-by: Josh Triplett <josh@...htriplett.org>
---
 scripts/coccinelle/misc/unnecessary-if.cocci | 40 ++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 scripts/coccinelle/misc/unnecessary-if.cocci

diff --git a/scripts/coccinelle/misc/unnecessary-if.cocci b/scripts/coccinelle/misc/unnecessary-if.cocci
new file mode 100644
index 0000000..7ed721f
--- /dev/null
+++ b/scripts/coccinelle/misc/unnecessary-if.cocci
@@ -0,0 +1,40 @@
+/// Remove unnecessary ifs with no statements.
+//
+// Confidence: High
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual report
+virtual context
+
+@r1 depends on patch@
+expression E, E2, f;
+@@
+(
+- if (
+      <+... \(f(...)\|++E\|--E\|E++\|E--\|E=E2\) ...+>
+- ) {}
++ ;
+|
+- if (E) {}
+)
+
+@r2 depends on report || context@
+expression E, E2, f;
+position p;
+@@
+(
+- if@p (
+      <+... \(f(...)\|++E\|--E\|E++\|E--\|E=E2\) ...+>
+- ) {}
++ ;
+|
+- if@p (E) {}
+)
+
+@...ipt:python depends on report@
+p << r2.p;
+@@
+
+msg = "WARNING: Unnecessary if with no body."
+coccilib.report.print_report(p[0], msg)
-- 
1.8.4.2

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