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[Ada] Allow pragma Inline_Always to overrule -fno-inline

Message ID 20150220094829.GA4495@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet Feb. 20, 2015, 9:48 a.m. UTC 
Prior to this change, -fno-inline was stopping all the inlining
unconditionally, even when requested with a pragma Inline_Always.

This was inconsistent with the behavior of the "always_inline" gcc attribute,
and this change fixes this.

It also removes an internal shortcircuit which was preventing consistency
checks of the various inlining pragmas attached to a subprogram.

For the following suprogram, the call to p1 must always be inlined
regardless of -fno-inline, and the call to p2 must not be inlined in
presence of -fno-inline:

procedure Intra is
   
   x : integer;
   pragma Import (C, X);
   pragma Volatile (X);
   
   procedure p1;
   pragma Inline_Always (p1);
   
   procedure p2;
   pragma Inline (p2);
   
   procedure p1 is begin x := 1; end;
   procedure p2 is begin x := 2; end;
begin
   p1;
   p2;
end;

And for the code below:

procedure Bogus is
   
   x : integer;
   pragma Import (C, X);
   pragma Volatile (X);
   
   procedure p1;
   pragma Inline_Always (p1);
   pragma No_Inline (p1);
   
   procedure p2;
   pragma Inline (p2);
   pragma No_Inline (p2);
   
   procedure p1 is begin x := 1; end;
   procedure p2 is begin x := 2; end;
begin
   p1;
   p2;
end;

The compiler must flag inconsistencies between No_Inline and Inline or
Inline_Always with or without -fno-inline on the command line.

Tested on x86_64-pc-linux-gnu, committed on trunk

2015-02-20  Olivier Hainque  <hainque@adacore.com>

	* opt.ads: Replace Opt.Suppress_All_Inlining by two separate
	flags controlling the actual FE inlining out of pragma Inline
	and pragma Inline_Always.
	* adabkend.adb (Scan_Compiler_Arguments): Set both flags to True
	on -fno-inline, which disables all inlining in compilers with
	an Ada back-end and without back-end inlining support.
	* back_end.adb (Scan_Back_End_Switches): Set the Inline related
	flag to True on -fno-inline and leave Inline_Always alone for
	gcc back-ends.
	* back_end.ads (Scan_Compiler_Arguments): Adjust spec wrt the
	names of the Opt flags it sets.
	* gnat1drv.adb (Adjust_Global_Switches): Remove test on
	Opt.Suppress_All_Inlining in the Back_End_Inlining computation.
	* sem_prag.adb (Make_Inline): Remove early return conditioned
	on Opt.Suppress_All_Inlining.
	* sem_ch6.adb (Analyze_Subprogram_Body_Helper): Use the flags to
	disable the calls to Build_Body_To_Inline otherwise triggered
	by pragma Inline or Inline_Always. This will prevent actual
	front-end inlining of the subprogram on calls.
diff mbox

Patch

Index: sem_prag.adb
===================================================================
--- sem_prag.adb	(revision 220835)
+++ sem_prag.adb	(working copy)
@@ -8204,12 +8204,6 @@ 
                Applies := True;
                return;
 
-            --  Ignore if all inlining is suppressed
-
-            elsif Suppress_All_Inlining then
-               Applies := True;
-               return;
-
             --  If inlining is not possible, for now do not treat as an error
 
             elsif Status /= Suppressed
Index: gnat1drv.adb
===================================================================
--- gnat1drv.adb	(revision 220835)
+++ gnat1drv.adb	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2014, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2015, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -609,13 +609,9 @@ 
 
       Back_End_Inlining :=
 
-        --  No back end inlining if inlining is suppressed
-
-        not Suppress_All_Inlining
-
         --  No back end inlining available for VM targets
 
-        and then VM_Target = No_VM
+        VM_Target = No_VM
 
         --  No back end inlining available on AAMP
 
Index: sem_ch6.adb
===================================================================
--- sem_ch6.adb	(revision 220835)
+++ sem_ch6.adb	(working copy)
@@ -3739,8 +3739,11 @@ 
          --  Legacy implementation (relying on frontend inlining)
 
          if not Back_End_Inlining then
-            if Has_Pragma_Inline_Always (Spec_Id)
-              or else (Has_Pragma_Inline (Spec_Id) and Front_End_Inlining)
+            if (Has_Pragma_Inline_Always (Spec_Id)
+                  and then not Opt.Disable_FE_Inline_Always)
+              or else
+              (Has_Pragma_Inline (Spec_Id) and then Front_End_Inlining
+                 and then not Opt.Disable_FE_Inline)
             then
                Build_Body_To_Inline (N, Spec_Id);
             end if;
Index: back_end.adb
===================================================================
--- back_end.adb	(revision 220835)
+++ back_end.adb	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---          Copyright (C) 1992-2014, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2015, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -23,6 +23,8 @@ 
 --                                                                          --
 ------------------------------------------------------------------------------
 
+--  This is the version of the Back_End package for GCC back ends
+
 with Atree;    use Atree;
 with Debug;    use Debug;
 with Elists;   use Elists;
@@ -251,11 +253,12 @@ 
          else
             Store_Compilation_Switch (Switch_Chars);
 
-            --  Back end switch -fno-inline also sets the Suppress_All_Inlining
-            --  front end flag to entirely inhibit all inlining.
+            --  For gcc back ends, -fno-inline disables Inline pragmas only,
+            --  not Inline_Always to remain consistent with the always_inline
+            --  attribute behavior.
 
             if Switch_Chars (First .. Last) = "fno-inline" then
-               Opt.Suppress_All_Inlining := True;
+               Opt.Disable_FE_Inline := True;
 
             --  Back end switch -fpreserve-control-flow also sets the front end
             --  flag that inhibits improper control flow transformations.
Index: back_end.ads
===================================================================
--- back_end.ads	(revision 220835)
+++ back_end.ads	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                 S p e c                                  --
 --                                                                          --
---          Copyright (C) 1992-2014, Free Software Foundation, Inc.         --
+--          Copyright (C) 1992-2015, Free Software Foundation, Inc.         --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -24,6 +24,7 @@ 
 ------------------------------------------------------------------------------
 
 --  Call the back end with all the information needed
+
 --  Note: there are multiple bodies/variants of this package, so do not
 --  modify this spec without coordination.
 
@@ -65,7 +66,8 @@ 
    --  This routine is expected to set the following to True if necessary (the
    --  default for all of these in Opt is False).
    --
-   --    Opt.Suppress_All_Inlining
+   --    Opt.Disable_FE_Inline
+   --    Opt.Disable_FE_Inline_Always
    --    Opt.Suppress_Control_Float_Optimizations
    --    Opt.Generate_SCO
    --    Opt.Generate_SCO_Instance_Table
Index: opt.ads
===================================================================
--- opt.ads	(revision 220839)
+++ opt.ads	(working copy)
@@ -1370,10 +1370,14 @@ 
    --  with'ed indirectly. It is set True by use of either the -gnatg or
    --  -gnaty switches, but not by use of the Style_Checks pragma.
 
-   Suppress_All_Inlining : Boolean := False;
+   Disable_FE_Inline        : Boolean := False;
+   Disable_FE_Inline_Always : Boolean := False;
    --  GNAT
-   --  Set by -fno-inline. Suppresses all inlining, both front end and back end
-   --  regardless of any other switches that are set.
+   --  Request to disable front end inlining from pragma Inline or pragma
+   --  Inline_Always out of the presence of the -fno-inline back end flag
+   --  on the command line, regardless of any other switches that are set.
+   --  It remains the back end's reponsibility to honor -fno-inline at the
+   --  back end level.
 
    Suppress_Control_Flow_Optimizations : Boolean := False;
    --  GNAT
Index: adabkend.adb
===================================================================
--- adabkend.adb	(revision 220835)
+++ adabkend.adb	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---                     Copyright (C) 2001-2014, AdaCore                     --
+--                     Copyright (C) 2001-2015, AdaCore                     --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -178,12 +178,13 @@ 
             return;
 
          --  Special check, the back end switch -fno-inline also sets the
-         --  front end flag to entirely inhibit all inlining. So we store it
-         --  and set the appropriate flag.
+         --  front end flags to entirely inhibit all inlining. So we store it
+         --  and set the appropriate flags.
 
          elsif Switch_Chars (First .. Last) = "fno-inline" then
             Lib.Store_Compilation_Switch (Switch_Chars);
-            Opt.Suppress_All_Inlining := True;
+            Opt.Disable_FE_Inline := True;
+            Opt.Disable_FE_Inline_Always := True;
             return;
 
          --  Similar processing for -fpreserve-control-flow