middle-end/101530 - fix shufflevector lowering
Commit Message
This makes __builtin_shufflevector lowering force the result
of the BIT_FIELD_REF lowpart operation to a temporary as to
fulfil the IL verifier constraint that BIT_FIELD_REFs should
be always in outermost handled component position. Trying to
enforce this during gimplification isn't as straight-forward
as here where we know we're dealing with an rvalue.
Bootstrap & regtest running on x86_64-unknown-linux-gnu - OK for trunk?
Thanks,
Richard.
2022-01-05 Richard Biener <rguenther@suse.de>
PR middle-end/101530
gcc/c-family/
* c-common.c (c_build_shufflevector): Wrap the BIT_FIELD_REF
in a TARGET_EXPR to force a temporary.
gcc/testsuite/
* c-c++-common/builtin-shufflevector-3.c: New testcase.
---
gcc/c-family/c-common.c | 5 +++++
.../c-c++-common/builtin-shufflevector-3.c | 15 +++++++++++++++
2 files changed, 20 insertions(+)
create mode 100644 gcc/testsuite/c-c++-common/builtin-shufflevector-3.c
Comments
On 1/5/2022 7:17 AM, Richard Biener via Gcc-patches wrote:
> This makes __builtin_shufflevector lowering force the result
> of the BIT_FIELD_REF lowpart operation to a temporary as to
> fulfil the IL verifier constraint that BIT_FIELD_REFs should
> be always in outermost handled component position. Trying to
> enforce this during gimplification isn't as straight-forward
> as here where we know we're dealing with an rvalue.
>
> Bootstrap & regtest running on x86_64-unknown-linux-gnu - OK for trunk?
>
> Thanks,
> Richard.
>
> 2022-01-05 Richard Biener <rguenther@suse.de>
>
> PR middle-end/101530
> gcc/c-family/
> * c-common.c (c_build_shufflevector): Wrap the BIT_FIELD_REF
> in a TARGET_EXPR to force a temporary.
>
> gcc/testsuite/
> * c-c++-common/builtin-shufflevector-3.c: New testcase.
Seems quite reasonable to me.
jeff
On Wed, 5 Jan 2022, Jeff Law wrote:
>
>
> On 1/5/2022 7:17 AM, Richard Biener via Gcc-patches wrote:
> > This makes __builtin_shufflevector lowering force the result
> > of the BIT_FIELD_REF lowpart operation to a temporary as to
> > fulfil the IL verifier constraint that BIT_FIELD_REFs should
> > be always in outermost handled component position. Trying to
> > enforce this during gimplification isn't as straight-forward
> > as here where we know we're dealing with an rvalue.
> >
> > Bootstrap & regtest running on x86_64-unknown-linux-gnu - OK for trunk?
> >
> > Thanks,
> > Richard.
> >
> > 2022-01-05 Richard Biener <rguenther@suse.de>
> >
> > PR middle-end/101530
> > gcc/c-family/
> > * c-common.c (c_build_shufflevector): Wrap the BIT_FIELD_REF
> > in a TARGET_EXPR to force a temporary.
> >
> > gcc/testsuite/
> > * c-c++-common/builtin-shufflevector-3.c: New testcase.
> Seems quite reasonable to me.
So I forgot to mark the TARGET_EXPR as having TREE_SIDE_EFFECTS
which makes the C++ FE side elide the initialization after
wrapping the TARGET_EXPR inside a COMPOUND_EXPR. Fixed as follows,
re-bootstrapped and tested on x86_64-unknown-linux-gnu and pushed.
Richard.
From be59671c5624fe8bf21ddb0192e97ebdfa4db381 Mon Sep 17 00:00:00 2001
From: Richard Biener <rguenther@suse.de>
Date: Wed, 5 Jan 2022 15:13:33 +0100
Subject: [PATCH] middle-end/101530 - fix shufflevector lowering
To: gcc-patches@gcc.gnu.org
This makes __builtin_shufflevector lowering force the result
of the BIT_FIELD_REF lowpart operation to a temporary as to
fulfil the IL verifier constraint that BIT_FIELD_REFs should
be always in outermost handled component position. Trying to
enforce this during gimplification isn't as straight-forward
as here where we know we're dealing with an rvalue.
FAIL: c-c++-common/torture/builtin-shufflevector-1.c -O0 execution test
2022-01-05 Richard Biener <rguenther@suse.de>
PR middle-end/101530
gcc/c-family/
* c-common.c (c_build_shufflevector): Wrap the BIT_FIELD_REF
in a TARGET_EXPR to force a temporary.
gcc/testsuite/
* c-c++-common/builtin-shufflevector-3.c: New testcase.
---
gcc/c-family/c-common.c | 7 +++++++
.../c-c++-common/builtin-shufflevector-3.c | 15 +++++++++++++++
2 files changed, 22 insertions(+)
create mode 100644 gcc/testsuite/c-c++-common/builtin-shufflevector-3.c
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 13341fa315e..4a6a4edb763 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -1243,6 +1243,13 @@ c_build_shufflevector (location_t loc, tree v0, tree v1,
tree lpartt = build_vector_type (TREE_TYPE (ret_type), mask.length ());
ret = build3_loc (loc, BIT_FIELD_REF,
lpartt, ret, TYPE_SIZE (lpartt), bitsize_zero_node);
+ /* Wrap the lowpart operation in a TARGET_EXPR so it gets a separate
+ temporary during gimplification. See PR101530 for cases where
+ we'd otherwise end up with non-toplevel BIT_FIELD_REFs. */
+ tree tem = create_tmp_var_raw (lpartt);
+ DECL_CONTEXT (tem) = current_function_decl;
+ ret = build4 (TARGET_EXPR, lpartt, tem, ret, NULL_TREE, NULL_TREE);
+ TREE_SIDE_EFFECTS (ret) = 1;
}
if (!c_dialect_cxx () && !wrap)
diff --git a/gcc/testsuite/c-c++-common/builtin-shufflevector-3.c b/gcc/testsuite/c-c++-common/builtin-shufflevector-3.c
new file mode 100644
index 00000000000..0c9bda689ef
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/builtin-shufflevector-3.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+
+typedef int __attribute__((__vector_size__ (sizeof(int)*4))) V;
+
+int
+foo(V v, int i)
+{
+ return __builtin_shufflevector (v, v, 2, 3)[i];
+}
+
+int
+bar(V v, int i)
+{
+ return __builtin_shufflevector(v, v, 4)[0] & i;
+}
@@ -1243,6 +1243,11 @@ c_build_shufflevector (location_t loc, tree v0, tree v1,
tree lpartt = build_vector_type (TREE_TYPE (ret_type), mask.length ());
ret = build3_loc (loc, BIT_FIELD_REF,
lpartt, ret, TYPE_SIZE (lpartt), bitsize_zero_node);
+ /* Wrap the lowpart operation in a TARGET_EXPR so it gets a separate
+ temporary during gimplification. See PR101530 for cases where
+ we'd otherwise end up with non-toplevel BIT_FIELD_REFs. */
+ tree tem = create_tmp_var_raw (lpartt);
+ ret = build4 (TARGET_EXPR, lpartt, tem, ret, NULL_TREE, NULL_TREE);
}
if (!c_dialect_cxx () && !wrap)
new file mode 100644
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+
+typedef int __attribute__((__vector_size__ (sizeof(int)*4))) V;
+
+int
+foo(V v, int i)
+{
+ return __builtin_shufflevector (v, v, 2, 3)[i];
+}
+
+int
+bar(V v, int i)
+{
+ return __builtin_shufflevector(v, v, 4)[0] & i;
+}