This patch fixes a bug in which symbol load instructions created by LRA
clobbered the SCC register, and therefore caused rare bad code bugs.
The patch now saves and restores SCC, if called during LRA. The save and
restore instructions are later optimized away if SCC isn't actually live.
Tested for amdgcn-unknown-amdhsa with no regressions.
Andrew Stubbs
Mentor Graphics / CodeSourcery
Fix scc clobber in movdi_symbol.
2019-03-27 Andrew Stubbs <a...@codesourcery.com>
gcc/
* config/gcn/gcn.md (CC_SAVE_REG): New constant.
(movdi): Call gen_movdi_symbol_save_scc.
(gen_movdi_symbol_save_scc): New insn and split.
diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index 4573a4ce32f..2b805a73c56 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -24,6 +24,7 @@
; Named registers
(define_constants
[(FIRST_SGPR_REG 0)
+ (CC_SAVE_REG 22)
(LAST_SGPR_REG 101)
(FLAT_SCRATCH_REG 102)
(FLAT_SCRATCH_LO_REG 102)
@@ -403,7 +404,10 @@
&& (GET_CODE (operands[1]) == SYMBOL_REF
|| GET_CODE (operands[1]) == LABEL_REF))
{
- emit_insn (gen_movdi_symbol (operands[0], operands[1]));
+ if (lra_in_progress)
+ emit_insn (gen_movdi_symbol_save_scc (operands[0], operands[1]));
+ else
+ emit_insn (gen_movdi_symbol (operands[0], operands[1]));
DONE;
}
})
@@ -826,6 +830,19 @@
[(set_attr "type" "mult")
(set_attr "length" "32")])
+(define_insn_and_split "movdi_symbol_save_scc"
+ [(set (match_operand:DI 0 "nonimmediate_operand" "=Sg")
+ (match_operand:DI 1 "general_operand" "Y"))
+ (clobber (reg:BI CC_SAVE_REG))]
+ "GET_CODE (operands[1]) == SYMBOL_REF || GET_CODE (operands[1]) == LABEL_REF
+ && (lra_in_progress || reload_completed)"
+ "#"
+ "reload_completed"
+ [(set (reg:BI CC_SAVE_REG) (reg:BI SCC_REG))
+ (parallel [(set (match_dup 0) (match_dup 1))
+ (clobber (reg:BI SCC_REG))])
+ (set (reg:BI SCC_REG) (reg:BI CC_SAVE_REG))])
+
(define_insn "gcn_indirect_call"
[(call (mem (match_operand:DI 0 "register_operand" "Sg"))
(match_operand 1 "" ""))
