[RFC/PATCH,v2,PR89245] Check REG_CALL_DECL note during the tail-merging

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  • [RFC/PATCH,v2,PR89245] Check REG_CALL_DECL note during the tail-merging
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Commit Message

Dragan Mladjenovic July 9, 2019, 8:06 p.m.
This patch prevents merging of CALL instructions that that have different
REG_CALL_DECL notes attached to them.

On most architectures this is not an important distinction. Usually instruction patterns
for calls to different functions reference different SYMBOL_REF-s, so they won't match.
On MIPS PIC calls get split into an got_load/*call_internal pair where the latter represents
indirect register call w/o SYMBOL_REF attached (until machine_reorg pass). The bugzilla issue
had such two internal_call-s merged despite the fact that they had different register usage
information assigned by ipa-ra.

As per comment form Richard Sandiford, this version compares reg usage for both call
instruction instead of shallow comparing the notes. Tests updated accordingly.

gcc/ChangeLog:

2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	* cfgcleanup.c (old_insns_match_p): Check if used hard regs set is equal
	for both call instructions.

gcc/testsuite/ChangeLog:

2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

	* gcc.target/mips/cfgcleanup-jalr1.c: New test.
	* gcc.target/mips/cfgcleanup-jalr2.c: New test.
	* gcc.target/mips/cfgcleanup-jalr3.c: New test.
---
 gcc/cfgcleanup.c                                 |  9 +++++++++
 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr1.c | 19 +++++++++++++++++++
 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr2.c | 23 +++++++++++++++++++++++
 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr3.c | 23 +++++++++++++++++++++++
 4 files changed, 74 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr1.c
 create mode 100644 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr2.c
 create mode 100644 gcc/testsuite/gcc.target/mips/cfgcleanup-jalr3.c

-- 
1.9.1

Comments

Jeff Law July 9, 2019, 9:21 p.m. | #1
On 7/9/19 2:06 PM, Dragan Mladjenovic wrote:
> This patch prevents merging of CALL instructions that that have different

> REG_CALL_DECL notes attached to them.

> 

> On most architectures this is not an important distinction. Usually instruction patterns

> for calls to different functions reference different SYMBOL_REF-s, so they won't match.

> On MIPS PIC calls get split into an got_load/*call_internal pair where the latter represents

> indirect register call w/o SYMBOL_REF attached (until machine_reorg pass). The bugzilla issue

> had such two internal_call-s merged despite the fact that they had different register usage

> information assigned by ipa-ra.

> 

> As per comment form Richard Sandiford, this version compares reg usage for both call

> instruction instead of shallow comparing the notes. Tests updated accordingly.

> 

> gcc/ChangeLog:

> 

> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

> 

> 	* cfgcleanup.c (old_insns_match_p): Check if used hard regs set is equal

> 	for both call instructions.

> 

> gcc/testsuite/ChangeLog:

> 

> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

> 

> 	* gcc.target/mips/cfgcleanup-jalr1.c: New test.

> 	* gcc.target/mips/cfgcleanup-jalr2.c: New test.

> 	* gcc.target/mips/cfgcleanup-jalr3.c: New test.

THanks.  I've installed this on the trunk.

jeff
Dragan Mladjenovic July 17, 2019, 8:29 a.m. | #2
On 09.07.2019. 23:21, Jeff Law wrote:
> On 7/9/19 2:06 PM, Dragan Mladjenovic wrote:

>> This patch prevents merging of CALL instructions that that have different

>> REG_CALL_DECL notes attached to them.

>>

>> On most architectures this is not an important distinction. Usually instruction patterns

>> for calls to different functions reference different SYMBOL_REF-s, so they won't match.

>> On MIPS PIC calls get split into an got_load/*call_internal pair where the latter represents

>> indirect register call w/o SYMBOL_REF attached (until machine_reorg pass). The bugzilla issue

>> had such two internal_call-s merged despite the fact that they had different register usage

>> information assigned by ipa-ra.

>>

>> As per comment form Richard Sandiford, this version compares reg usage for both call

>> instruction instead of shallow comparing the notes. Tests updated accordingly.

>>

>> gcc/ChangeLog:

>>

>> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

>>

>> 	* cfgcleanup.c (old_insns_match_p): Check if used hard regs set is equal

>> 	for both call instructions.

>>

>> gcc/testsuite/ChangeLog:

>>

>> 2019-07-09  Dragan Mladjenovic  <dmladjenovic@wavecomp.com>

>>

>> 	* gcc.target/mips/cfgcleanup-jalr1.c: New test.

>> 	* gcc.target/mips/cfgcleanup-jalr2.c: New test.

>> 	* gcc.target/mips/cfgcleanup-jalr3.c: New test.

> THanks.  I've installed this on the trunk.

>

> jeff

Thanks. Can this be back-ported to active branches also. This issue 
seems to be there
since gcc6 if not gcc5.

Thanks in advance,

Dragan

Patch

diff --git a/gcc/cfgcleanup.c b/gcc/cfgcleanup.c
index 992912c..fca3a08 100644
--- a/gcc/cfgcleanup.c
+++ b/gcc/cfgcleanup.c
@@ -53,6 +53,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "dce.h"
 #include "dbgcnt.h"
 #include "rtl-iter.h"
+#include "regs.h"
 
 #define FORWARDER_BLOCK_P(BB) ((BB)->flags & BB_FORWARDER_BLOCK)
 
@@ -1224,6 +1225,14 @@  old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx_insn *i1, rtx_insn *i2)
 		}
 	    }
 	}
+
+      HARD_REG_SET i1_used, i2_used;
+
+      get_call_reg_set_usage (i1, &i1_used, call_used_reg_set);
+      get_call_reg_set_usage (i2, &i2_used, call_used_reg_set);
+
+      if (!hard_reg_set_equal_p (i1_used, i2_used))
+        return dir_none;
     }
 
   /* If both i1 and i2 are frame related, verify all the CFA notes
diff --git a/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr1.c b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr1.c
new file mode 100644
index 0000000..24c1826
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr1.c
@@ -0,0 +1,19 @@ 
+/* { dg-do compile } */
+/* { dg-options "-mabicalls -fpic -mno-mips16 -mno-micromips" } */
+/* { dg-skip-if "needs codesize optimization" { *-*-* } { "-O0" "-O1" "-O2" "-O3" } { "" } } */
+
+extern void foo (void*);
+
+extern void bar (void*);
+
+void
+test (void* p)
+{
+   if (!p)
+	foo(p);
+   else
+	bar(p);
+}
+
+/* { dg-final { scan-assembler-not "\\\.reloc\t1f,R_MIPS_JALR,foo" } } */
+/* { dg-final { scan-assembler-not "\\\.reloc\t1f,R_MIPS_JALR,bar" } } */
diff --git a/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr2.c b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr2.c
new file mode 100644
index 0000000..9fd75c9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr2.c
@@ -0,0 +1,23 @@ 
+/* { dg-do compile } */
+/* { dg-options "-mabicalls -fpic -mno-mips16 -mno-micromips" } */
+/* { dg-additional-options "-fno-inline -fipa-ra -mcompact-branches=never" } */
+/* { dg-skip-if "needs codesize optimization" { *-*-* } { "-O0" "-O1" "-O2" "-O3" } { "" } } */
+
+static int foo (void* p) { __asm__ (""::"r"(p):"$t0"); return 0; }
+
+static int bar (void* p) { return 1; }
+
+int
+test (void* p)
+{
+  int res = !p ? foo(p) : bar(p);
+
+  register int tmp __asm__("$t0") = -1;
+  __asm__ (""::"r"(tmp));
+
+  return res;
+}
+
+/* { dg-final { scan-assembler "\\\.reloc\t1f,R_MIPS_JALR,foo" } } */
+/* { dg-final { scan-assembler "\\\.reloc\t1f,R_MIPS_JALR,bar" } } */
+/* { dg-final { scan-assembler-not "\\.set\tnomacro\n\tjalr\t\\\$25" } } */
diff --git a/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr3.c b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr3.c
new file mode 100644
index 0000000..580c6ec
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/cfgcleanup-jalr3.c
@@ -0,0 +1,23 @@ 
+/* { dg-do compile } */
+/* { dg-options "-mabicalls -fpic -mno-mips16 -mno-micromips" } */
+/* { dg-additional-options "-fno-inline -fipa-ra -mcompact-branches=never" } */
+/* { dg-skip-if "needs codesize optimization" { *-*-* } { "-O0" "-O1" "-O2" "-O3" } { "" } } */
+
+static int foo (void* p) { return 0; }
+
+static int bar (void* p) { return 1; }
+
+int
+test (void* p)
+{
+  int res = !p ? foo(p) : bar(p);
+
+  register int tmp __asm__("$t0") = -1;
+  __asm__ (""::"r"(tmp));
+
+  return res;
+}
+
+/* { dg-final { scan-assembler-not "\\\.reloc\t1f,R_MIPS_JALR,foo" } } */
+/* { dg-final { scan-assembler-not "\\\.reloc\t1f,R_MIPS_JALR,bar" } } */
+/* { dg-final { scan-assembler "\\.set\tnomacro\n\tjalr\t\\\$25" } } */