linux-kernel - Re: [PATCH 2/2] gcov: re-drop support for clang-10

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Message-ID: <20210407190749.p3h72h4zlshiyt76@google.com>
Date:   Wed, 7 Apr 2021 12:07:49 -0700
From:   Fangrui Song <maskray@...gle.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Peter Oberparleiter <oberpar@...ux.ibm.com>,
        Nathan Chancellor <nathan@...nel.org>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Prasad Sodagudi <psodagud@...cinc.com>
Subject: Re: [PATCH 2/2] gcov: re-drop support for clang-10


On 2021-04-07, Nick Desaulniers wrote:
>LLVM changed the expected function signatures for
>llvm_gcda_emit_function() in the clang-11 release.  Drop the older
>implementations and require folks to upgrade their compiler if they're
>interested in GCOV support.
>
>Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
>---
> kernel/gcov/clang.c | 40 ----------------------------------------
> 1 file changed, 40 deletions(-)
>
>diff --git a/kernel/gcov/clang.c b/kernel/gcov/clang.c
>index 1747204541bf..78c4dc751080 100644
>--- a/kernel/gcov/clang.c
>+++ b/kernel/gcov/clang.c
>@@ -69,9 +69,6 @@ struct gcov_fn_info {
>
> 	u32 ident;
> 	u32 checksum;
>-#if CONFIG_CLANG_VERSION < 110000
>-	u8 use_extra_checksum;
>-#endif
> 	u32 cfg_checksum;
>
> 	u32 num_counters;
>@@ -113,23 +110,6 @@ void llvm_gcda_start_file(const char *orig_filename, u32 version, u32 checksum)
> }
> EXPORT_SYMBOL(llvm_gcda_start_file);
>
>-#if CONFIG_CLANG_VERSION < 110000
>-void llvm_gcda_emit_function(u32 ident, u32 func_checksum,
>-		u8 use_extra_checksum, u32 cfg_checksum)
>-{
>-	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
>-
>-	if (!info)
>-		return;
>-
>-	INIT_LIST_HEAD(&info->head);
>-	info->ident = ident;
>-	info->checksum = func_checksum;
>-	info->use_extra_checksum = use_extra_checksum;
>-	info->cfg_checksum = cfg_checksum;
>-	list_add_tail(&info->head, &current_info->functions);
>-}
>-#else
> void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum)
> {
> 	struct gcov_fn_info *info = kzalloc(sizeof(*info), GFP_KERNEL);
>@@ -143,7 +123,6 @@ void llvm_gcda_emit_function(u32 ident, u32 func_checksum, u32 cfg_checksum)
> 	info->cfg_checksum = cfg_checksum;
> 	list_add_tail(&info->head, &current_info->functions);
> }
>-#endif
> EXPORT_SYMBOL(llvm_gcda_emit_function);
>
> void llvm_gcda_emit_arcs(u32 num_counters, u64 *counters)
>@@ -274,16 +253,8 @@ int gcov_info_is_compatible(struct gcov_info *info1, struct gcov_info *info2)
> 		!list_is_last(&fn_ptr2->head, &info2->functions)) {
> 		if (fn_ptr1->checksum != fn_ptr2->checksum)
> 			return false;
>-#if CONFIG_CLANG_VERSION < 110000
>-		if (fn_ptr1->use_extra_checksum != fn_ptr2->use_extra_checksum)
>-			return false;
>-		if (fn_ptr1->use_extra_checksum &&
>-			fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
>-			return false;
>-#else
> 		if (fn_ptr1->cfg_checksum != fn_ptr2->cfg_checksum)
> 			return false;
>-#endif
> 		fn_ptr1 = list_next_entry(fn_ptr1, head);
> 		fn_ptr2 = list_next_entry(fn_ptr2, head);
> 	}
>@@ -403,21 +374,10 @@ size_t convert_to_gcda(char *buffer, struct gcov_info *info)
> 		u32 i;
>
> 		pos += store_gcov_u32(buffer, pos, GCOV_TAG_FUNCTION);
>-#if CONFIG_CLANG_VERSION < 110000
>-		pos += store_gcov_u32(buffer, pos,
>-			fi_ptr->use_extra_checksum ? 3 : 2);
>-#else
> 		pos += store_gcov_u32(buffer, pos, 3);
>-#endif
> 		pos += store_gcov_u32(buffer, pos, fi_ptr->ident);
> 		pos += store_gcov_u32(buffer, pos, fi_ptr->checksum);
>-#if CONFIG_CLANG_VERSION < 110000
>-		if (fi_ptr->use_extra_checksum)
>-			pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
>-#else
> 		pos += store_gcov_u32(buffer, pos, fi_ptr->cfg_checksum);
>-#endif
>-
> 		pos += store_gcov_u32(buffer, pos, GCOV_TAG_COUNTER_BASE);
> 		pos += store_gcov_u32(buffer, pos, fi_ptr->num_counters * 2);
> 		for (i = 0; i < fi_ptr->num_counters; i++)
>-- 
>2.31.1.295.g9ea45b61b8-goog
>

Looks good for both. Thanks!

Reviewed-by: Fangrui Song <maskray@...gle.com>