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答复: [AArch64][SVE][IPA] ICE caused by incompatibility of SRA and svst builtin-function

Message ID 8FB10B4CA53A144E918874949D50CEB1022B336A@dggeml528-mbx.china.huawei.com
State New
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Series 答复: [AArch64][SVE][IPA] ICE caused by incompatibility of SRA and svst builtin-function | expand

Commit Message

bule April 7, 2020, 2:57 a.m. UTC

The patch is tested and works fine. It is more appropriate to handle the context by considering it as a section of assemble code.

A minor question is that I think svst functions are for store operations. Why pass ISRA_CTX_LOAD to scan_expr_access rather than ISRA_CTX_STORE?

Bu Le

发件人: Martin Jambor [mailto:mjambor@suse.cz] 
发送时间: 2020年4月7日 7:21
收件人: bule <bule1@huawei.com>
抄送: Richard Biener <richard.guenther@gmail.com>; gcc-patches@gcc.gnu.org
主题: Re: [AArch64][SVE][IPA] ICE caused by incompatibility of SRA and svst builtin-function


On Thu, Apr 02 2020, Richard Biener wrote:
> On Thu, Apr 2, 2020 at 5:36 AM bule <bule1@huawei.com> wrote:
>> Hello,
>> An Internal Compiler Error(ICE) is found in ipa-sra optimization pass when it handle the argument of internal call svst3 for SVE.
>> The problem comes from gcc/testsuite/gcc.target/aarch64/sve/acle/asm/st2_bf16.c in the test suit, which can be reduced to flowing code:
>> #include <arm_sve.h>
>> #include<arm_bf16.h>
>> void st2_bf16_base (svbfloat16x3_t z1, svbool_t p0, bfloat16_t *x0, intptr_t x1) {
>>     svst3 (p0, x0, z1);
>> }
>> Compiled with -march=armv8.2-a+sve -msve-vector-bits=256 -O2, it will result in a segment fault in IPA-SRA:
>> > [bule@localhost gcc10_fail]$ gcc st2_bf16.i -o st2_bf16.s -S 
>> > -march=armv8.2-a+sve -msve-vector-bits=256 -O2 during IPA pass: sra
>> > st2_bf16.c: In function ‘st2_bf16_base’:
>> > st2_bf16.c:10:1: internal compiler error: Segmentation fault
>> >   ...... /* omit some stack info here.  */ ......
>> > 0xa34f68 call_summary<isra_call_summary*>::get_create(cgraph_edge*)
>> >         ../.././gcc/symbol-summary.h:642
>> > 0xa34f68 record_nonregister_call_use
>> >         ../.././gcc/ipa-sra.c:1613
>> > 0xa34f68 scan_expr_access
>> >         ../.././gcc/ipa-sra.c:1781
>> >   ...... /* omit some stack info here.  */ ......
>> > Please submit a full bug report,
>> > with preprocessed source if appropriate.
>> > Please include the complete backtrace with any bug report.
>> Details can be found in PR 94398.
>> Similar problem can be found in svst2、svst4 and other functions of this kind.
>> This problem is cause by "record_nonregister_call_use" function trying to access the call graph edge of an internal call, .MASK_STORE_LANE, which is a NULL pointer.
>> The reason of stepping into "record_nonregister_call_use" function is that the upper level function "scan_expr_access" considered the "svbfloat16x3_t z1"
>> argument as a valid candidate for further optimization.
>> A simple solution here is to disqualify the candidate at "scan_expr_access" level when the call graph edge is null, which indicates the call is either an internal call or a call with no references. For both case, the further optimization process should stop before it reference a NULL pointer.
>> A proposed patch is attached.
>> Any suggestions?
> I think internal calls should be handled like asms which means, lookig 
> at the source a bit, instead of ISRA_CTX_ARG pass ISRA_CTX_LOAD to 
> scan_expr_access.

indeed, in this situation it would be best if we simply treated such arguments as loads (from the aggregates).  Would the following (only very mildly tested) patch work for you?


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diff --git a/gcc/ipa-sra.c b/gcc/ipa-sra.c index f0ebaec708d..b225af61427 100644
--- a/gcc/ipa-sra.c
+++ b/gcc/ipa-sra.c
@@ -1870,15 +1870,22 @@  scan_function (cgraph_node *node, struct function *fun)
            case GIMPLE_CALL:
                unsigned argument_count = gimple_call_num_args (stmt);
-               scan_call_info call_info;
+               isra_scan_context ctx = ISRA_CTX_ARG;
+               scan_call_info call_info, *call_info_p = &call_info;
                call_info.cs = node->get_edge (stmt);
-               call_info.argument_count = argument_count;
+               if (!call_info.cs)
+                 {
+                   call_info_p = NULL;
+                   ctx = ISRA_CTX_LOAD;
+                 }
+               else
+                 call_info.argument_count = argument_count;
                for (unsigned i = 0; i < argument_count; i++)
                    call_info.arg_idx = i;
                    scan_expr_access (gimple_call_arg (stmt, i), stmt,
-                                     ISRA_CTX_ARG, bb, &call_info);
+                                     ctx, bb, call_info_p);
                tree lhs = gimple_call_lhs (stmt);