[gcc r10-10008] d: Wrong evaluation order of binary expressions (PR101640)

[gcc r10-10008] d: Wrong evaluation order of binary expressions (PR101640)

[Iain Buclaw]

https://gcc.gnu.org/g:9a16492f524eb46b4ba0375d2e2ebe0f62b72fa4

commit r10-10008-g9a16492f524eb46b4ba0375d2e2ebe0f62b72fa4
Author: Iain Buclaw <ibuclaw@gdcproject.org>
Date:   Tue Jul 27 13:24:34 2021 +0200

    d: Wrong evaluation order of binary expressions (PR101640)
    
    The use of fold_build2 can in some cases swap the order of its operands
    if that is the more optimal thing to do.  However this breaks semantic
    guarantee of left-to-right evaluation in D.
    
            PR d/101640
    
    gcc/d/ChangeLog:
    
            * expr.cc (binary_op): Use build2 instead of fold_build2.
    
    gcc/testsuite/ChangeLog:
    
            * gdc.dg/pr101640.d: New test.
    
    (cherry picked from commit 54ec50bada94a8ff92edb04ee5216c27fa4bf942)

Diff:
---
 gcc/d/expr.cc                   |  2 +-
 gcc/testsuite/gdc.dg/pr101640.d | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/gcc/d/expr.cc b/gcc/d/expr.cc
index 2e70bf3a8e7..955a0ad4ad4 100644
--- a/gcc/d/expr.cc
+++ b/gcc/d/expr.cc
@@ -162,7 +162,7 @@ class ExprVisitor : public Visitor
 	    eptype = type;
 	  }
 
-	ret = fold_build2 (code, eptype, arg0, arg1);
+	ret = build2 (code, eptype, arg0, arg1);
       }
 
     return d_convert (type, ret);
diff --git a/gcc/testsuite/gdc.dg/pr101640.d b/gcc/testsuite/gdc.dg/pr101640.d
new file mode 100644
index 00000000000..68de4088512
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr101640.d
@@ -0,0 +1,11 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101640
+// { dg-do compile }
+// { dg-options "-fdump-tree-original" }
+
+int fun101640(ref int);
+
+int test101640(int val)
+{
+    // { dg-final { scan-tree-dump "= val \\\+ fun101640 \\\(\\\(int &\\\) &val\\\);" "original" } }
+    return val + fun101640(val);
+}