From: Senthil Kumar Selvaraj <senthilkumar.selvaraj@microchip.com>
Date: Mon, 17 Dec 2018 13:26:50 +0000 (+0000)
Subject: backport: re PR rtl-optimization/88253 (Inlining of function incorrectly deletes... 
X-Git-Tag: releases/gcc-7.5.0~717
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=80ad71d18983467ff41b7f99aef25e1b2b647c7c;p=thirdparty%2Fgcc.git

backport: re PR rtl-optimization/88253 (Inlining of function incorrectly deletes volatile register access when using XOR in avr-gcc)

2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>

	Backport from trunk
	2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>

	PR rtl-optimization/88253
	* combine.c (combine_simplify_rtx): Test for side-effects before
	substituting by zero.

2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>

	Backport from trunk
	2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>

	PR rtl-optimization/88253
	* gcc.target/avr/pr88253.c: New test.

From-SVN: r267201
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index fc096324ec29..d1507bfb50f7 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	Backport from trunk
+	2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	PR rtl-optimization/88253
+	* combine.c (combine_simplify_rtx): Test for side-effects before
+	substituting by zero.
+
 2018-12-15  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	Backport from trunk
diff --git a/gcc/combine.c b/gcc/combine.c
index bc023d2f994a..56f7f4912343 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -5807,8 +5807,9 @@ combine_simplify_rtx (rtx x, machine_mode op0_mode, int in_dest,
 	    && GET_MODE_PRECISION (mode) < GET_MODE_PRECISION (op0_mode)
 	    && subreg_lowpart_offset (mode, op0_mode) == SUBREG_BYTE (x)
 	    && HWI_COMPUTABLE_MODE_P (op0_mode)
-	    && (nonzero_bits (SUBREG_REG (x), op0_mode)
-		& GET_MODE_MASK (mode)) == 0)
+	    && ((nonzero_bits (SUBREG_REG (x), op0_mode)
+		 & GET_MODE_MASK (mode)) == 0)
+	    && !side_effects_p (SUBREG_REG (x)))
 	  return CONST0_RTX (mode);
       }
 
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c9c464fcef2c..8344276af915 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	Backport from trunk
+	2018-12-17  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
+
+	PR rtl-optimization/88253
+	* gcc.target/avr/pr88253.c: New test.
+
 2018-12-15  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/88138
diff --git a/gcc/testsuite/gcc.target/avr/pr88253.c b/gcc/testsuite/gcc.target/avr/pr88253.c
new file mode 100644
index 000000000000..7fa7e4efc691
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/pr88253.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-Os -w" } */
+ 
+static int aRead() __attribute__((always_inline));
+static int aRead() {
+    unsigned char h,l;
+    l = (*(volatile unsigned char *)(0x78)) ;
+    h = (*(volatile unsigned char *)(0x79)) ;
+    return (h<<8) | l;
+}
+ 
+int main() {
+    volatile unsigned char x;
+     x = aRead()^42;
+ }
+ /* { dg-final { scan-assembler "lds r\\d+,121" } } */