[gcc/devel/omp/gcc-12] gcn: Fix __builtin_gcn_first_call_this_thread_p

[gcc/devel/omp/gcc-12] gcn: Fix __builtin_gcn_first_call_this_thread_p

[Tobias Burnus]

https://gcc.gnu.org/g:ec5445902910ad709f33a0f13fcd314b3d4e3e87

commit ec5445902910ad709f33a0f13fcd314b3d4e3e87
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Mon Nov 28 15:21:30 2022 +0100

    gcn: Fix __builtin_gcn_first_call_this_thread_p
    
    Contrary naive expectation, unspec_volatile (via prologue_use) did not
    prevent the cprop pass (at -O2) to remove the access to the s[0:1]
    (PRIVATE_SEGMENT_BUFFER_ARG) register as the volatile got just put on
    the preceeding pseudoregister.  Solution: Use gen_rtx_USE instead.
    Additionally, this patch removes (gen_)prologue_use_di as it is then no
    longer used.
    
    Finally, as we already do bit manipulation, instead of using the full
    64bit side - and then just keeping the value of 's0', just move directly
    to use only s1 of s[0:1] and do the bit manipulations there, generating
    more readable assembly code and better matching the '#else' branch.
    
    gcc/ChangeLog:
    
            * config/gcn/gcn.cc (gcn_expand_builtin_1): Work on s1 instead
            of s[0:1] and use USE to prevent removal of setting that register.
            * config/gcn/gcn.md (prologue_use_di): Remove.
    
    (cherry picked from commit 9fa67f1c1228a852e23943a41e68b664172c654c)

Diff:
---
 gcc/ChangeLog.omp     |  9 +++++++++
 gcc/config/gcn/gcn.cc | 16 ++++++++--------
 gcc/config/gcn/gcn.md | 13 -------------
 3 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index f8a49af7620..48443438e39 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,12 @@
+2022-11-28  Tobias Burnus  <tobias@codesourcery.com>
+
+	Backported from master:
+	2022-11-28  Tobias Burnus  <tobias@codesourcery.com>
+
+	* config/gcn/gcn.cc (gcn_expand_builtin_1): Work on s1 instead
+	of s[0:1] and use USE to prevent removal of setting that register.
+	* config/gcn/gcn.md (prologue_use_di): Remove.
+
 2022-11-26  Sandra Loosemore  <sandra@codesourcery.com>
 
 	Backported from master:
diff --git a/gcc/config/gcn/gcn.cc b/gcc/config/gcn/gcn.cc
index 48a80ba103c..85f20a46d67 100644
--- a/gcc/config/gcn/gcn.cc
+++ b/gcc/config/gcn/gcn.cc
@@ -4589,8 +4589,9 @@ gcn_expand_builtin_1 (tree exp, rtx target, rtx /*subtarget */ ,
 	    rtx not_first = gen_label_rtx ();
 	    rtx reg = gen_rtx_REG (DImode,
 			cfun->machine->args.reg[PRIVATE_SEGMENT_BUFFER_ARG]);
-	    rtx cmp = force_reg (DImode,
-				 gen_rtx_LSHIFTRT (DImode, reg, GEN_INT (48)));
+	    reg = gcn_operand_part (DImode, reg, 1);
+	    rtx cmp = force_reg (SImode,
+				 gen_rtx_LSHIFTRT (SImode, reg, GEN_INT (16)));
 	    emit_insn (gen_cstoresi4 (result, gen_rtx_NE (BImode, cmp,
 							  GEN_INT(12345)),
 				      cmp, GEN_INT(12345)));
@@ -4598,12 +4599,11 @@ gcn_expand_builtin_1 (tree exp, rtx target, rtx /*subtarget */ ,
 							      const0_rtx),
 				       result));
 	    emit_move_insn (reg,
-	      force_reg (DImode,
-		gen_rtx_IOR (DImode,
-			     gen_rtx_AND (DImode, reg,
-					  GEN_INT (0x0000ffffffffffffL)),
-			     GEN_INT (12345L << 48))));
-	    emit_insn (gen_prologue_use (reg));
+	      force_reg (SImode,
+		gen_rtx_IOR (SImode,
+			     gen_rtx_AND (SImode, reg, GEN_INT (0x0000ffff)),
+			     GEN_INT (12345L << 16))));
+	    emit_insn (gen_rtx_USE (VOIDmode, reg));
 	    emit_label (not_first);
 	  }
 	return result;
diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index f31c20471da..7e803f738bc 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -726,19 +726,6 @@
   ""
   [(set_attr "length" "0")])
 
-(define_insn_and_split "prologue_use_di"
-  [(unspec_volatile [(match_operand:DI 0 "register_operand")] UNSPECV_PROLOGUE_USE)]
-  ""
-  "#"
-  "reload_completed"
-  [(unspec_volatile [(match_dup 0)] UNSPECV_PROLOGUE_USE)
-   (unspec_volatile [(match_dup 1)] UNSPECV_PROLOGUE_USE)]
-  {
-    operands[1] = gcn_operand_part (DImode, operands[0], 1);
-    operands[0] = gcn_operand_part (DImode, operands[0], 0);
-  }
-  [(set_attr "length" "0")])
-
 (define_expand "prologue"
   [(const_int 0)]
   ""