Workaround-rustc-1.37-code-generation-issue-on-ppc.patch

0001-Workaround-rustc-1.37-code-generation-issue-on-ppc.patch

From 934fbe8f307027dd54d6c89e1c713cd59d02b820 Mon Sep 17 00:00:00 2001
From: Colin Samples <colin.samples+git@gmail.com>
Date: Sat, 21 Sep 2019 14:00:21 -0400
Subject: [PATCH] Workaround rustc 1.37 code generation issue on ppc

This patch works around an issue where rustc v1.37 emits incorrect code for
rsvg_internal::rect::intersect(), resulting in an incorrect x coordinate for the
intersection rectangle, which trips an assertion in librsvg. This issue does not
occur with rustc v1.36, v1.38 beta, or v1.39 nightly.

The patch forces a volatile access for the x coordinate when compiled for
ppc64le, which corrects the code generation.
---
 rsvg_internals/src/rect.rs | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/rsvg_internals/src/rect.rs b/rsvg_internals/src/rect.rs
index f1ab4ed5..2fd32f68 100644
--- a/rsvg_internals/src/rect.rs
+++ b/rsvg_internals/src/rect.rs
@@ -2,6 +2,19 @@ use cairo;
 
 use crate::float_eq_cairo::ApproxEqCairo;
 
+#[cfg(target_arch = "powerpc64")]
+use std::ptr;
+
+#[cfg(target_arch = "powerpc64")]
+fn get_x1(x1: &f64) -> f64 {
+    unsafe { ptr::read_volatile(x1) }
+}
+
+#[cfg(not(target_arch = "powerpc64"))]
+fn get_x1(x1: &f64) -> f64 {
+    *x1
+}
+
 pub trait RectangleExt {
     fn new(x: f64, y: f64, width: f64, height: f64) -> cairo::Rectangle;
     fn is_empty(&self) -> bool;
@@ -35,7 +48,7 @@ impl RectangleExt for cairo::Rectangle {
 
         if x2 > x1 && y2 > y1 {
             cairo::Rectangle {
-                x: x1,
+                x: get_x1(&x1),
                 y: y1,
                 width: x2 - x1,
                 height: y2 - y1,
-- 
2.23.0