On Mon, Jan 29, 2024 at 9:34 AM H.J. Lu <hjl.to...@gmail.com> wrote: > > On Mon, Jan 29, 2024 at 9:00 AM Jakub Jelinek <ja...@redhat.com> wrote: > > > > On Mon, Jan 29, 2024 at 08:45:45AM -0800, H.J. Lu wrote: > > > In this case, these are internal to the same comdat group: > > > > But that is only by accident, no? > > This may be by luck. I don't know if gcc checks it when > generating such references. > > > I mean, if you need to refer to such a symbol from > > non-comdat function or comdat function in a different comdat group > > and RA decides it wants the constant in memory rather than code? > > Your patch uses > > if (decl) > > return targetm.asm_out.function_rodata_section (decl, ???); > > and default_function_rodata_section only looks at comdat group of the > > passed in decl. But the decl here is what the constant refers to, not > > who is referring it.
LRA puts a function symbol reference in a constant pool via #0 force_const_mem (in_mode=E_DImode, x=0x7fffe9e7e000) at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/varasm.cc:3951 #1 0x0000000001833870 in curr_insn_transform (check_only_p=false) at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/lra-constraints.cc:4473 #2 0x0000000001836eae in lra_constraints (first_p=true) at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/lra-constraints.cc:5462 #3 0x000000000181fcf1 in lra (f=0x0, verbose=5) at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/lra.cc:2442 #4 0x00000000017c8828 in do_reload () at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/ira.cc:5973 #5 0x00000000017c8d25 in (anonymous namespace)::pass_reload::execute ( this=0x48d8730) at /export/gnu/import/git/gitlab/x86-gcc-test/gcc/ira.cc:6161 for (gdb) call debug_rtx (curr_insn) (insn 12 57 15 2 (set (reg:V2DI 101 [ _16 ]) (vec_concat:V2DI (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE10_M_managerERNS_9_Any_dataERKSI_NS_18_Manager_operationE") [flags 0x3] <function_decl 0x7fffe9e2a600 _M_manager>) (reg/f:DI 109))) 7521 {vec_concatv2di} (expr_list:REG_DEAD (reg/f:DI 110) (expr_list:REG_DEAD (reg/f:DI 109) (expr_list:REG_EQUIV (vec_concat:V2DI (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE10_M_managerERNS_9_Any_dataERKSI_NS_18_Manager_operationE") [flags 0x3] <function_decl 0x7fffe9e2a600 _M_manager>) (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE9_M_invokeERKNS_9_Any_dataE") [flags 0x3] <function_decl 0x7fffe9e2a700 _M_invoke>)) (nil))))) (gdb) CONST_POOL_OK_P doesn't check if it is safe to do so for function symbols. Here is a patch to add the check. -- H.J.
From 1947920740e48cdc8076299f8cc58e797ec39a7c Mon Sep 17 00:00:00 2001 From: "H.J. Lu" <hjl.to...@gmail.com> Date: Mon, 29 Jan 2024 12:53:32 -0800 Subject: [PATCH] lra: Add const_pool_reference_ok LRA may put a function symbol reference in (gdb) call debug_rtx (curr_insn) (insn 12 57 15 2 (set (reg:V2DI 101 [ _16 ]) (vec_concat:V2DI (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE10_M_managerERNS_9_Any_dataERKSI_NS_18_Manager_operationE") [flags 0x3] <function_decl 0x7fffe9e2a600 _M_manager>) (reg/f:DI 109))) 7521 {vec_concatv2di} (expr_list:REG_DEAD (reg/f:DI 110) (expr_list:REG_DEAD (reg/f:DI 109) (expr_list:REG_EQUIV (vec_concat:V2DI (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE10_M_managerERNS_9_Any_dataERKSI_NS_18_Manager_operationE") [flags 0x3] <function_decl 0x7fffe9e2a600 _M_manager>) (symbol_ref:DI ("_ZN4blah17_Function_handlerIFvvENS_5_BindIFPFvPvxxxEPN3vtk6detail3smp27vtkSMPTools_FunctorInternalIN12_GLOBAL__N_19CountUsesIxEELb0EEExxxEEEE9_M_invokeERKNS_9_Any_dataE") [flags 0x3] <function_decl 0x7fffe9e2a700 _M_invoke>)) (nil))))) (gdb) in the constant pool. But it isn't safe when the referenced function symbol is in a different COMDAT group from the current instruction function body if the function symbol isn't public. Add const_pool_reference_ok to check if a function symbol can be forced into the constant pool. PR rtl-optimization/113617 * lra-constraints.cc (const_pool_reference_ok): New. (CONST_POOL_OK_P): Use. --- gcc/lra-constraints.cc | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/gcc/lra-constraints.cc b/gcc/lra-constraints.cc index 0ae81c1ff9c..59e6944c245 100644 --- a/gcc/lra-constraints.cc +++ b/gcc/lra-constraints.cc @@ -925,6 +925,35 @@ operands_match_p (rtx x, rtx y, int y_hard_regno) return true; } +/* Return true if the symbol X can be referenced in the function + FUNC_DECL. */ + +static bool +const_pool_reference_ok (tree func_decl, rtx x) +{ + /* It is OK if there is no COMDAT or X isn't a symbol. */ + if (!HAVE_COMDAT_GROUP || GET_CODE (x) != SYMBOL_REF) + return true; + + tree decl = SYMBOL_REF_DECL (x); + /* It is OK if X isn't a function symbol. */ + if (TREE_CODE (decl) != FUNCTION_DECL) + return true; + + tree comdat_group = DECL_COMDAT_GROUP (decl); + /* It is OK if X isn't a COMDAT symbol. */ + if (!comdat_group) + return true; + + /* It is OK if X and FUNC_DECL are in the same COMDAT group. */ + if (comdat_group == DECL_COMDAT_GROUP (func_decl)) + return true; + + /* X is referenced from a different COMDAT group. Return true only + if X is a public symbol. */ + return TREE_PUBLIC (decl) != 0; +} + /* True if X is a constant that can be forced into the constant pool. MODE is the mode of the operand, or VOIDmode if not known. */ #define CONST_POOL_OK_P(MODE, X) \ @@ -932,6 +961,7 @@ operands_match_p (rtx x, rtx y, int y_hard_regno) && CONSTANT_P (X) \ && GET_CODE (X) != HIGH \ && GET_MODE_SIZE (MODE).is_constant () \ + && const_pool_reference_ok (cfun->decl, X) \ && !targetm.cannot_force_const_mem (MODE, X)) /* If REG is a reload pseudo, try to make its class satisfying CL. */ -- 2.43.0