[llvm-branch-commits] [llvm] release/19.x: [RISCV] Don't outline pcrel_lo when the function has a section prefix (#107943) (PR #108288)

Tobias Hieta via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Mon Sep 16 11:31:13 PDT 2024


https://github.com/tru updated https://github.com/llvm/llvm-project/pull/108288

>From a847b66a750291f8b63c03b9f355c6f4d09cdfe3 Mon Sep 17 00:00:00 2001
From: Jonathon Penix <jpenix at quicinc.com>
Date: Wed, 11 Sep 2024 09:53:11 -0700
Subject: [PATCH] [RISCV] Don't outline pcrel_lo when the function has a
 section prefix (#107943)

GNU ld will error when encountering a pcrel_lo whose corresponding
pcrel_hi is in a different section. [1] introduced a check to help
prevent this issue by preventing outlining in a few circumstances.
However, we can also hit this same issue when outlining from functions
with prefixes ("hot"/"unlikely"/"unknown" from profile information, for
example) as the outlined function might not have the same prefix,
possibly resulting in a "paired" pcrel_lo and pcrel_hi ending up in
different sections.

To prevent this issue, take a similar approach as [1] and additionally
prevent outlining when we see a pcrel_lo and the function has a prefix.

[1]
https://github.com/llvm/llvm-project/commit/96c85f80f0d615ffde0f85d8270e0a8c9f4e5430

Fixes #107520

(cherry picked from commit 866b93e6b33fac9a4bc62bbc32199bd98f434784)
---
 llvm/lib/Target/RISCV/RISCVInstrInfo.cpp      |   2 +-
 .../RISCV/machineoutliner-pcrel-lo.mir        | 104 +++++++++++++++++-
 2 files changed, 99 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
index ba3b4bd701d634..6c0cbeadebf431 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.cpp
@@ -2902,7 +2902,7 @@ RISCVInstrInfo::getOutliningTypeImpl(MachineBasicBlock::iterator &MBBI,
     // if any possible.
     if (MO.getTargetFlags() == RISCVII::MO_PCREL_LO &&
         (MI.getMF()->getTarget().getFunctionSections() || F.hasComdat() ||
-         F.hasSection()))
+         F.hasSection() || F.getSectionPrefix()))
       return outliner::InstrType::Illegal;
   }
 
diff --git a/llvm/test/CodeGen/RISCV/machineoutliner-pcrel-lo.mir b/llvm/test/CodeGen/RISCV/machineoutliner-pcrel-lo.mir
index 8a83543b0280fd..fd3630bcfad256 100644
--- a/llvm/test/CodeGen/RISCV/machineoutliner-pcrel-lo.mir
+++ b/llvm/test/CodeGen/RISCV/machineoutliner-pcrel-lo.mir
@@ -18,6 +18,9 @@
   define i32 @foo2(i32 %a, i32 %b) comdat { ret i32 0 }
 
   define i32 @foo3(i32 %a, i32 %b) section ".abc" { ret i32 0 }
+
+  define i32 @foo4(i32 %a, i32 %b) !section_prefix !0 { ret i32 0 }
+  !0 = !{!"function_section_prefix", !"myprefix"}
 ...
 ---
 name:            foo
@@ -27,23 +30,24 @@ body:             |
   ; CHECK: bb.0:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.1:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.2:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11, implicit $x13
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.3:
   ; CHECK-NEXT:   PseudoRET
+  ;
   ; CHECK-FS-LABEL: name: foo
   ; CHECK-FS: bb.0:
   ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
@@ -109,26 +113,27 @@ body:             |
   ; CHECK: bb.0:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
   ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.1:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
   ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.2:
   ; CHECK-NEXT:   liveins: $x10, $x11, $x13
   ; CHECK-NEXT: {{  $}}
-  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_1, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
   ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
   ; CHECK-NEXT:   PseudoBR %bb.3
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.3:
   ; CHECK-NEXT:   PseudoRET
+  ;
   ; CHECK-FS-LABEL: name: foo2
   ; CHECK-FS: bb.0:
   ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
@@ -223,6 +228,7 @@ body:             |
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT: bb.3:
   ; CHECK-NEXT:   PseudoRET
+  ;
   ; CHECK-FS-LABEL: name: foo3
   ; CHECK-FS: bb.0:
   ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
@@ -289,3 +295,89 @@ body:             |
   bb.3:
     PseudoRET
 ...
+---
+name:            foo4
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: foo4
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-NEXT:   PseudoBR %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-NEXT:   PseudoBR %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2:
+  ; CHECK-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-NEXT:   PseudoBR %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT:   PseudoRET
+  ;
+  ; CHECK-FS-LABEL: name: foo4
+  ; CHECK-FS: bb.0:
+  ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-FS-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-FS-NEXT:   PseudoBR %bb.3
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT: bb.1:
+  ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-FS-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-FS-NEXT:   PseudoBR %bb.3
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT: bb.2:
+  ; CHECK-FS-NEXT:   liveins: $x10, $x11, $x13
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT:   $x5 = PseudoCALLReg target-flags(riscv-call) @OUTLINED_FUNCTION_0, implicit-def $x5, implicit-def $x10, implicit-def $x11, implicit-def $x12, implicit $x10, implicit $x11
+  ; CHECK-FS-NEXT:   $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+  ; CHECK-FS-NEXT:   PseudoBR %bb.3
+  ; CHECK-FS-NEXT: {{  $}}
+  ; CHECK-FS-NEXT: bb.3:
+  ; CHECK-FS-NEXT:   PseudoRET
+  bb.0:
+    liveins: $x10, $x11, $x13
+
+    $x11 = ORI $x11, 1023
+    $x12 = ADDI $x10, 17
+    $x11 = AND $x12, $x11
+    $x10 = SUB $x10, $x11
+    $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+    PseudoBR %bb.3
+
+  bb.1:
+    liveins: $x10, $x11, $x13
+
+    $x11 = ORI $x11, 1023
+    $x12 = ADDI $x10, 17
+    $x11 = AND $x12, $x11
+    $x10 = SUB $x10, $x11
+    $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+    PseudoBR %bb.3
+
+  bb.2:
+    liveins: $x10, $x11, $x13
+
+    $x11 = ORI $x11, 1023
+    $x12 = ADDI $x10, 17
+    $x11 = AND $x12, $x11
+    $x10 = SUB $x10, $x11
+    $x11 = LW killed renamable $x13, target-flags(riscv-pcrel-lo) <mcsymbol .Lpcrel_hi1> :: (dereferenceable load (s32) from @bar)
+    PseudoBR %bb.3
+
+  bb.3:
+    PseudoRET
+...



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