[PATCH] D71282: Fix bug 44190 - wrong code with #pragma pack(1)

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl created this revision.
yaxunl added reviewers: rjmccall, efriedma, jnspaulsson.

https://github.com/llvm/llvm-project/commit/5b330e8d6122c336d81dfd11c864e6c6240a381e caused
a regression on s390:

https://bugs.llvm.org/show_bug.cgi?id=44190

we need to copy if if either the argument is non-byval or the argument is underaligned.


https://reviews.llvm.org/D71282

Files:
  clang/lib/CodeGen/CGCall.cpp
  clang/test/CodeGen/s390x-packed-struct-func-arg.c


Index: clang/test/CodeGen/s390x-packed-struct-func-arg.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/s390x-packed-struct-func-arg.c
@@ -0,0 +1,23 @@
+// RUN: %clang_cc1 -triple s390x-linux-gnu -target-cpu z13 -emit-llvm -o - %s \
+// RUN:     | FileCheck %s
+
+struct S0 {
+  long f1;
+  int f2 : 4;
+} d;
+
+#pragma pack(1)
+struct S1 {
+  struct S0 S0_member;
+};
+
+void f(struct S0 arg) {
+  arg.f2 = 1;
+}
+
+void g() {
+  struct S1 g;
+  // CHECK: alloca %struct.S0, align 8
+  // CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 {{.*}}, i8* align 1 {{.*}}, i64 16
+  f(g.S0_member);
+}
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -4004,9 +4004,8 @@
           auto LV = I->getKnownLValue();
           auto AS = LV.getAddressSpace();
 
-          if ((!ArgInfo.getIndirectByVal() &&
-               (LV.getAlignment() >=
-                getContext().getTypeAlignInChars(I->Ty)))) {
+          if ((!ArgInfo.getIndirectByVal() ||
+               (LV.getAlignment() < getContext().getTypeAlignInChars(I->Ty)))) {
             NeedCopy = true;
           }
           if (!getLangOpts().OpenCL) {


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