From: Andreas Krebbel Date: Thu, 21 Apr 2016 11:50:22 +0000 (+0000) Subject: PR70674: S/390: Add memory barrier to stack pointer restore X-Git-Tag: releases/gcc-4.9.4~213 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27977a5f4fea39348c02afc978eaab51a5c99e9c;p=thirdparty%2Fgcc.git PR70674: S/390: Add memory barrier to stack pointer restore PR70674: S/390: Add memory barrier to stack pointer restore from fpr. This patches fixes a problem with stack variable accesses being scheduled after the stack pointer restore instructions. In the testcase this happened with the stack variable 'a' accessed through the frame pointer. The existing stack_tie we have in the backend is basically useless when trying to block stack variable accesses from being scheduled across an insn. The alias set of stack variables and the frame alias set usually differ and hence aren't in conflict with each other. The solution appears to be a magic MEM term with a scratch register which is handled as a full memory barrier when analyzing scheduling dependencies. With the patch a (clobber (mem:BLK (scratch))) is being added to the restore instruction in order to prevent any memory operations to be scheduled across the insn. The patch does that only for the one case where the stack pointer is restored from an FPR. Theoretically this might happen also in the case where the stack pointer gets restored using a load multiple. However, triggering that problem with load-multiple appears to be much harder since the load-multiple will restore the frame pointer as well. So in order to see the problem a different call-clobbered register would need to be used as temporary stack pointer. Another case which needs to be handled some day is the stack pointer allocation part. It needs to be a memory barrier as well. gcc/ChangeLog: 2016-04-21 Andreas Krebbel Backport from mainline 2016-04-20 Andreas Krebbel PR target/70674 * config/s390/s390.c (s390_restore_gprs_from_fprs): Pick the new stack_restore_from_fpr pattern when restoring r15. (s390_optimize_prologue): Strip away the memory barrier in the parallel when trying to get rid of restore insns. * config/s390/s390.md ("stack_restore_from_fpr"): New insn definition for loading the stack pointer from an FPR. Compared to the normal move insn this pattern includes a full memory barrier. gcc/testsuite/ChangeLog: 2016-04-21 Andreas Krebbel Backport from mainline 2016-04-20 Andreas Krebbel PR target/70674 * gcc.target/s390/pr70674.c: New test. From-SVN: r235334 --- diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 4f31fc743301..d6d083faddde 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,17 @@ +2016-04-21 Andreas Krebbel + + Backport from mainline + 2016-04-20 Andreas Krebbel + + PR target/70674 + * config/s390/s390.c (s390_restore_gprs_from_fprs): Pick the new + stack_restore_from_fpr pattern when restoring r15. + (s390_optimize_prologue): Strip away the memory barrier in the + parallel when trying to get rid of restore insns. + * config/s390/s390.md ("stack_restore_from_fpr"): New insn + definition for loading the stack pointer from an FPR. Compared to + the normal move insn this pattern includes a full memory barrier. + 2016-04-13 Kyrylo Tkachov Backport from mainline diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c index 2a52db9e9e4f..af910b9cacfb 100644 --- a/gcc/config/s390/s390.c +++ b/gcc/config/s390/s390.c @@ -8615,19 +8615,25 @@ s390_restore_gprs_from_fprs (void) for (i = 6; i < 16; i++) { - if (FP_REGNO_P (cfun_gpr_save_slot (i))) - { - rtx insn = - emit_move_insn (gen_rtx_REG (DImode, i), - gen_rtx_REG (DImode, cfun_gpr_save_slot (i))); - df_set_regs_ever_live (i, true); - add_reg_note (insn, REG_CFA_RESTORE, gen_rtx_REG (DImode, i)); - if (i == STACK_POINTER_REGNUM) - add_reg_note (insn, REG_CFA_DEF_CFA, - plus_constant (Pmode, stack_pointer_rtx, - STACK_POINTER_OFFSET)); - RTX_FRAME_RELATED_P (insn) = 1; - } + rtx insn; + + if (!FP_REGNO_P (cfun_gpr_save_slot (i))) + continue; + + rtx fpr = gen_rtx_REG (DImode, cfun_gpr_save_slot (i)); + + if (i == STACK_POINTER_REGNUM) + insn = emit_insn (gen_stack_restore_from_fpr (fpr)); + else + insn = emit_move_insn (gen_rtx_REG (DImode, i), fpr); + + df_set_regs_ever_live (i, true); + add_reg_note (insn, REG_CFA_RESTORE, gen_rtx_REG (DImode, i)); + if (i == STACK_POINTER_REGNUM) + add_reg_note (insn, REG_CFA_DEF_CFA, + plus_constant (Pmode, stack_pointer_rtx, + STACK_POINTER_OFFSET)); + RTX_FRAME_RELATED_P (insn) = 1; } } @@ -10912,37 +10918,46 @@ s390_optimize_prologue (void) /* Remove ldgr/lgdr instructions used for saving and restore GPRs if possible. */ - if (TARGET_Z10 - && GET_CODE (pat) == SET - && GET_MODE (SET_SRC (pat)) == DImode - && REG_P (SET_SRC (pat)) - && REG_P (SET_DEST (pat))) + if (TARGET_Z10) { - int src_regno = REGNO (SET_SRC (pat)); - int dest_regno = REGNO (SET_DEST (pat)); - int gpr_regno; - int fpr_regno; + rtx tmp_pat = pat; - if (!((GENERAL_REGNO_P (src_regno) && FP_REGNO_P (dest_regno)) - || (FP_REGNO_P (src_regno) && GENERAL_REGNO_P (dest_regno)))) - continue; + if (INSN_CODE (insn) == CODE_FOR_stack_restore_from_fpr) + tmp_pat = XVECEXP (pat, 0, 0); - gpr_regno = GENERAL_REGNO_P (src_regno) ? src_regno : dest_regno; - fpr_regno = FP_REGNO_P (src_regno) ? src_regno : dest_regno; + if (GET_CODE (tmp_pat) == SET + && GET_MODE (SET_SRC (tmp_pat)) == DImode + && REG_P (SET_SRC (tmp_pat)) + && REG_P (SET_DEST (tmp_pat))) + { + int src_regno = REGNO (SET_SRC (tmp_pat)); + int dest_regno = REGNO (SET_DEST (tmp_pat)); + int gpr_regno; + int fpr_regno; + + if (!((GENERAL_REGNO_P (src_regno) + && FP_REGNO_P (dest_regno)) + || (FP_REGNO_P (src_regno) + && GENERAL_REGNO_P (dest_regno)))) + continue; - /* GPR must be call-saved, FPR must be call-clobbered. */ - if (!call_really_used_regs[fpr_regno] - || call_really_used_regs[gpr_regno]) - continue; + gpr_regno = GENERAL_REGNO_P (src_regno) ? src_regno : dest_regno; + fpr_regno = FP_REGNO_P (src_regno) ? src_regno : dest_regno; - /* It must not happen that what we once saved in an FPR now - needs a stack slot. */ - gcc_assert (cfun_gpr_save_slot (gpr_regno) != -1); + /* GPR must be call-saved, FPR must be call-clobbered. */ + if (!call_really_used_regs[fpr_regno] + || call_really_used_regs[gpr_regno]) + continue; - if (cfun_gpr_save_slot (gpr_regno) == 0) - { - remove_insn (insn); - continue; + /* It must not happen that what we once saved in an FPR now + needs a stack slot. */ + gcc_assert (cfun_gpr_save_slot (gpr_regno) != -1); + + if (cfun_gpr_save_slot (gpr_regno) == 0) + { + remove_insn (insn); + continue; + } } } diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md index 986b0c65b9a3..cc9e39ef6c43 100644 --- a/gcc/config/s390/s390.md +++ b/gcc/config/s390/s390.md @@ -183,6 +183,8 @@ (BASE_REGNUM 13) ; Return address register. (RETURN_REGNUM 14) + ; Stack pointer register. + (STACK_REGNUM 15) ; Condition code register. (CC_REGNUM 33) ; Thread local storage pointer register. @@ -9896,6 +9898,14 @@ [(set_attr "length" "0")]) +(define_insn "stack_restore_from_fpr" + [(set (reg:DI STACK_REGNUM) + (match_operand:DI 0 "register_operand" "f")) + (clobber (mem:BLK (scratch)))] + "TARGET_Z10" + "lgdr\t%%r15,%0" + [(set_attr "op_type" "RRE")]) + ; ; Data prefetch patterns ; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 324810d7bb46..868b415670f7 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,11 @@ +2016-04-21 Andreas Krebbel + + Backport from mainline + 2016-04-20 Andreas Krebbel + + PR target/70674 + * gcc.target/s390/pr70674.c: New test. + 2016-04-13 Kyrylo Tkachov Backport from mainline diff --git a/gcc/testsuite/gcc.target/s390/pr70674.c b/gcc/testsuite/gcc.target/s390/pr70674.c new file mode 100644 index 000000000000..13bf271d95ff --- /dev/null +++ b/gcc/testsuite/gcc.target/s390/pr70674.c @@ -0,0 +1,13 @@ +/* Test case for PR/70674. */ + +/* { dg-do compile { target s390x-*-* } } */ +/* { dg-options "-march=z10 -mtune=z196 -O2 -fno-omit-frame-pointer -fno-asynchronous-unwind-tables" } */ + +void +foo (void) +{ + volatile int a = 5; + (void) a; +} + +/* { dg-final { scan-assembler-not "^.*lgdr.*\n.*\\(%r11\\)" } } */