[lld] 64c73d5 - Reland [lld][LoongArch] Relax call36/tail36: R_LARCH_CALL36

via llvm-commits llvm-commits at lists.llvm.org
Sun Mar 9 20:07:39 PDT 2025


Author: Zhaoxin Yang
Date: 2025-03-10T11:02:23+08:00
New Revision: 64c73d5c7184d1287e4982684d0fe8ad5f2341c0

URL: https://github.com/llvm/llvm-project/commit/64c73d5c7184d1287e4982684d0fe8ad5f2341c0
DIFF: https://github.com/llvm/llvm-project/commit/64c73d5c7184d1287e4982684d0fe8ad5f2341c0.diff

LOG: Reland [lld][LoongArch] Relax call36/tail36: R_LARCH_CALL36

Instructions with relocation `R_LARCH_CALL36` may be relax as follows:
```
From:
   pcaddu18i $dest, %call36(foo)
     R_LARCH_CALL36, R_LARCH_RELAX
   jirl $r, $dest, 0
To:
   b/bl foo  # bl if r=$ra, b if r=$zero
     R_LARCH_B26
```

This patch fixes the buildbots failuer of lld tests.
Changes: Modify test files: from `sym at plt` to `%plt(sym)`.

Added: 
    lld/test/ELF/loongarch-relax-call36-2.s
    lld/test/ELF/loongarch-relax-call36.s

Modified: 
    lld/ELF/Arch/LoongArch.cpp
    lld/test/ELF/loongarch-relax-emit-relocs.s

Removed: 
    


################################################################################
diff  --git a/lld/ELF/Arch/LoongArch.cpp b/lld/ELF/Arch/LoongArch.cpp
index dbf024eadf100..d9e4066c17ea8 100644
--- a/lld/ELF/Arch/LoongArch.cpp
+++ b/lld/ELF/Arch/LoongArch.cpp
@@ -58,6 +58,8 @@ enum Op {
   LD_W = 0x28800000,
   LD_D = 0x28c00000,
   JIRL = 0x4c000000,
+  B = 0x50000000,
+  BL = 0x54000000,
 };
 
 enum Reg {
@@ -830,6 +832,37 @@ static void relaxPCHi20Lo12(Ctx &ctx, const InputSection &sec, size_t i,
   remove = 4;
 }
 
+// Relax code sequence.
+// From:
+//   pcaddu18i $ra, %call36(foo)
+//   jirl $ra, $ra, 0
+// To:
+//   b/bl foo
+static void relaxCall36(Ctx &ctx, const InputSection &sec, size_t i,
+                        uint64_t loc, Relocation &r, uint32_t &remove) {
+  const uint64_t dest =
+      (r.expr == R_PLT_PC ? r.sym->getPltVA(ctx) : r.sym->getVA(ctx)) +
+      r.addend;
+
+  const int64_t displace = dest - loc;
+  // Check if the displace aligns 4 bytes or exceeds the range of b[l].
+  if ((displace & 0x3) != 0 || !isInt<28>(displace))
+    return;
+
+  const uint32_t nextInsn = read32le(sec.content().data() + r.offset + 4);
+  if (getD5(nextInsn) == R_RA) {
+    // convert jirl to bl
+    sec.relaxAux->relocTypes[i] = R_LARCH_B26;
+    sec.relaxAux->writes.push_back(insn(BL, 0, 0, 0));
+    remove = 4;
+  } else if (getD5(nextInsn) == R_ZERO) {
+    // convert jirl to b
+    sec.relaxAux->relocTypes[i] = R_LARCH_B26;
+    sec.relaxAux->writes.push_back(insn(B, 0, 0, 0));
+    remove = 4;
+  }
+}
+
 static bool relax(Ctx &ctx, InputSection &sec) {
   const uint64_t secAddr = sec.getVA();
   const MutableArrayRef<Relocation> relocs = sec.relocs();
@@ -874,6 +907,10 @@ static bool relax(Ctx &ctx, InputSection &sec) {
       if (isPairRelaxable(relocs, i))
         relaxPCHi20Lo12(ctx, sec, i, loc, r, relocs[i + 2], remove);
       break;
+    case R_LARCH_CALL36:
+      if (relaxable(relocs, i))
+        relaxCall36(ctx, sec, i, loc, r, remove);
+      break;
     }
 
     // For all anchors whose offsets are <= r.offset, they are preceded by
@@ -977,6 +1014,10 @@ void LoongArch::finalizeRelax(int passes) const {
             // RelExpr is needed for relocating.
             r.expr = r.sym->hasFlag(NEEDS_PLT) ? R_PLT_PC : R_PC;
             break;
+          case R_LARCH_B26:
+            skip = 4;
+            write32le(p, aux.writes[writesIdx++]);
+            break;
           default:
             llvm_unreachable("unsupported type");
           }

diff  --git a/lld/test/ELF/loongarch-relax-call36-2.s b/lld/test/ELF/loongarch-relax-call36-2.s
new file mode 100644
index 0000000000000..383913dbe6277
--- /dev/null
+++ b/lld/test/ELF/loongarch-relax-call36-2.s
@@ -0,0 +1,65 @@
+# REQUIRES: loongarch
+## Relax R_LARCH_CALL36. This test tests boundary cases and some special symbols.
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=loongarch64 -mattr=+relax a.s -o a.o
+
+# RUN: ld.lld -T lds a.o -o a
+# RUN: llvm-objdump -d --no-show-raw-insn a | FileCheck %s --check-prefixes=RELAX,RELAX-MID
+
+## Unsure whether this needs a diagnostic. GNU ld allows this.
+# RUN: ld.lld -T lds -pie a.o -o a.pie
+# RUN: llvm-objdump -d --no-show-raw-insn a.pie | FileCheck %s --check-prefixes=RELAX,RELAX-MID
+
+# RUN: ld.lld -T lds -pie -z notext -z ifunc-noplt a.o -o a.ifunc-noplt
+# RUN: llvm-objdump -d --no-show-raw-insn a.ifunc-noplt | FileCheck %s --check-prefixes=RELAX,NORELAX-MID
+
+# RELAX-LABEL:  <_start>:
+## offset = 0x10000000 - 0x8000000 = 0x8000000(134217728), hi=512, lo18=0
+# RELAX-NEXT:    8000000:  pcaddu18i $ra, 512
+# RELAX-NEXT:              jirl   $ra, $ra, 0
+# RELAX-NEXT:              bl     134217720
+# RELAX-NEXT:              bl     -134217728
+## offset = 12 - 0x8000010 = -0x8000004(-134217732), hi=512, lo18=-4
+# RELAX-NEXT:    8000010:  pcaddu18i $ra, -512
+# RELAX-NEXT:              jirl   $ra, $ra, -4
+# RELAX-EMPTY:
+
+# RELAX-MID-LABEL:  <.mid>:
+## offset = 0x8010000 - 0x8008000 = 32768
+# RELAX-MID-NEXT:    8008000:  bl     32768
+# RELAX-MID-NEXT:              b      32764
+# RELAX-MID-EMPTY:
+
+# NORELAX-MID-LABEL: <.mid>:
+# NORELAX-MID-NEXT:  8008000:  pcaddu18i $ra, 0
+# NORELAX-MID-NEXT:            jirl   $ra, $ra, 0
+# NORELAX-MID-NEXT:            pcaddu18i $t0, 0
+# NORELAX-MID-NEXT:            jr     $t0
+# NORELAX-MID-EMPTY:
+
+#--- a.s
+.global _start, ifunc
+_start:
+  call36 pos       # exceed positive range (.text+0x7fffffc), not relaxed
+  call36 pos       # relaxed
+  call36 neg       # relaxed
+  call36 neg       # exceed negative range (.text+16-0x8000000), not relaxed
+
+.section .mid,"ax", at progbits
+.balign 16
+  call36 ifunc      # enable ifunc, not relaxed
+  tail36 $t0, ifunc # enable ifunc, not relaxed
+
+.type ifunc, @gnu_indirect_function
+ifunc:
+  ret
+
+#--- lds
+SECTIONS {
+  .text 0x8000000 : { *(.text) }
+  .mid  0x8008000 : { *(.mid) }
+  .iplt 0x8010000 : { *(.iplt) }
+}
+neg = 12;
+pos = 0x10000000;

diff  --git a/lld/test/ELF/loongarch-relax-call36.s b/lld/test/ELF/loongarch-relax-call36.s
new file mode 100644
index 0000000000000..fa6e79dfa5803
--- /dev/null
+++ b/lld/test/ELF/loongarch-relax-call36.s
@@ -0,0 +1,136 @@
+# REQUIRES: loongarch
+## Relax R_LARCH_CALL36, which involves the macro instructions call36/tail36.
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+
+# RUN: llvm-mc -filetype=obj -triple=loongarch64 -mattr=+relax a.s -o a.64.o
+# RUN: llvm-mc -filetype=obj -triple=loongarch64 -mattr=+relax b.s -o b.64.o
+# RUN: ld.lld -shared -soname=b.so b.64.o -o b.64.so
+# RUN: ld.lld -T lds a.64.o b.64.so -o 64
+# RUN: llvm-objdump -td --no-show-raw-insn 64 | FileCheck %s --check-prefix=RELAX
+
+## --no-relax disables relaxation.
+# RUN: ld.lld -T lds a.64.o b.64.so --no-relax -o 64.norelax
+# RUN: llvm-objdump -td --no-show-raw-insn 64.norelax | FileCheck %s --check-prefix=NORELAX
+
+# RELAX:       {{0*}}00010000 g       .text  {{0*}}0000001c _start
+# RELAX:       {{0*}}0001001c g       .text  {{0*}}00000000 _start_end
+# RELAX:       {{0*}}00010808 g       .mid   {{0*}}00000000 mid_end
+# RELAX:       {{0*}}10010010 g       .high  {{0*}}00000000 high_end
+
+# RELAX-LABEL: <_start>:
+## offset = 0x10018 - 0x10000 = 24
+# RELAX-NEXT:      10000:  bl     24 <a>
+# RELAX-NEXT:              b      20 <a>
+# RELAX-NEXT:              nop
+# RELAX-NEXT:              nop
+## offset = .plt(0x10400)+32 - 0x10010 = 1040
+# RELAX-NEXT:      10010:  bl     1040 <bar+0x10420>
+# RELAX-NEXT:              b      1036 <bar+0x10420>
+# RELAX-EMPTY:
+# RELAX-NEXT: <a>:
+# RELAX-NEXT:      10018:  ret
+# RELAX-EMPTY:
+
+# RELAX-LABEL: <.mid>:
+## offset = 0x10000 - 0x10800 = -2048
+# RELAX-NEXT:      10800:  bl     -2048 <_start>
+# RELAX-NEXT:              b      -2052 <_start>
+# RELAX-EMPTY:
+
+# RELAX-LABEL: <.mid2>:
+## offset = 0x10000 - 0x1010000 = -16777216
+# RELAX-NEXT:    1010000:  bl     -16777216 <_start>
+# RELAX-NEXT:              b      -16777220 <_start>
+# RELAX-EMPTY:
+
+# RELAX-LABEL: <.high>:
+## offset = 0x10000 - 0x10010000 = -0x10000000, hi=-1024, lo18=0
+# RELAX-NEXT:   10010000:  pcaddu18i $ra, -1024
+# RELAX-NEXT:              jirl   $ra, $ra, 0
+# RELAX-NEXT:              pcaddu18i $t0, -1024
+# RELAX-NEXT:              jirl   $zero, $t0, -8
+# RELAX-EMPTY:
+
+
+# NORELAX-LABEL: <_start>:
+## offset = 0x10020 - 0x10000 = 0x20, hi=0, lo18=32
+# NORELAX-NEXT:    10000:  pcaddu18i $ra, 0
+# NORELAX-NEXT:            jirl   $ra, $ra, 32
+## offset = 0x10020 - 0x10008 = 0x18, hi=0, lo18=24
+# NORELAX-NEXT:    10008:  pcaddu18i $t0, 0
+# NORELAX-NEXT:            jirl   $zero, $t0, 24
+## offset = .plt(0x10400)+32 - 0x10010 = 0x410, hi=0, lo18=1040
+# NORELAX-NEXT:    10010:  pcaddu18i $ra, 0
+# NORELAX-NEXT:            jirl   $ra, $ra, 1040
+## offset = .plt(0x10400)+32 - 0x10018 = 0x408, hi=0, lo18=1032
+# NORELAX-NEXT:    10018:  pcaddu18i $t0, 0
+# NORELAX-NEXT:            jirl   $zero, $t0, 1032
+# NORELAX-EMPTY:
+# NORELAX-NEXT: <a>:
+# NORELAX-NEXT:      10020:  ret
+# NORELAX-EMPTY:
+
+# NORELAX-LABEL: <.mid>:
+## offset = 0x10000 - 0x10800 = -0x800, hi=0, lo18=-2048
+# NORELAX-NEXT:    10800:  pcaddu18i $ra, 0
+# NORELAX-NEXT:            jirl   $ra, $ra, -2048
+# NORELAX-NEXT:            pcaddu18i $t0, 0
+# NORELAX-NEXT:            jirl   $zero, $t0, -2056
+# NORELAX-EMPTY:
+
+# NORELAX-LABEL: <.mid2>:
+## offset = 0x10000 - 0x1010000 = -0x1000000, hi=-64, lo18=0
+# NORELAX-NEXT:  1010000:  pcaddu18i $ra, -64
+# NORELAX-NEXT:            jirl   $ra, $ra, 0
+# NORELAX-NEXT:            pcaddu18i $t0, -64
+# NORELAX-NEXT:            jirl   $zero, $t0, -8
+# NORELAX-EMPTY:
+
+# NORELAX-LABEL: <.high>:
+## offset = 0x10000 - 0x10010000 = -0x10000000, hi=-1024, lo18=0
+# NORELAX-NEXT: 10010000:  pcaddu18i $ra, -1024
+# NORELAX-NEXT:            jirl   $ra, $ra, 0
+# NORELAX-NEXT:            pcaddu18i $t0, -1024
+# NORELAX-NEXT:            jirl   $zero, $t0, -8
+# NORELAX-EMPTY:
+
+#--- a.s
+.global _start, _start_end
+_start:
+  call36 a          # relaxed. la64: bl
+  tail36 $t0, a     # relaxed. la64: b
+.balign 16
+  call36 bar        # PLT call36 can be relaxed. la64: bl
+  tail36 $t0, bar   # PLT tail36 can be relaxed. la64: bl
+
+a:
+  ret
+.size _start, . - _start
+_start_end:
+
+.section .mid,"ax", at progbits
+  call36 _start         # relaxed. la64: bl
+  tail36 $t0, _start    # relaxed. la64: b
+
+.section .mid2,"ax", at progbits
+  call36 _start         # relaxed. la64: bl
+  tail36 $t0, _start    # relaxed. la64: b
+
+.section .high,"ax", at progbits
+  call36 _start         # exceed range, not relaxed
+  tail36 $t0, _start    # exceed range, not relaxed
+
+#--- b.s
+.globl bar
+bar:
+  ret
+
+#--- lds
+SECTIONS {
+  .text 0x10000 : { *(.text) }
+  .plt 0x10400 : { *(.plt) }
+  .mid 0x10800 : { *(.mid); mid_end = .; }
+  .mid2 0x1010000 : { *(.mid2) }
+  .high 0x10010000 : { *(.high); high_end = .; }
+}

diff  --git a/lld/test/ELF/loongarch-relax-emit-relocs.s b/lld/test/ELF/loongarch-relax-emit-relocs.s
index 7031ffd9f6686..f70d391b465e3 100644
--- a/lld/test/ELF/loongarch-relax-emit-relocs.s
+++ b/lld/test/ELF/loongarch-relax-emit-relocs.s
@@ -2,11 +2,11 @@
 ## Test that we can handle --emit-relocs while relaxing.
 
 # RUN: llvm-mc --filetype=obj --triple=loongarch32 --mattr=+relax %s -o %t.32.o
-# RUN: llvm-mc --filetype=obj --triple=loongarch64 --mattr=+relax %s -o %t.64.o
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 --mattr=+relax --defsym ELF64=1 %s -o %t.64.o
 # RUN: ld.lld -Ttext=0x10000 -section-start=.got=0x20000 --emit-relocs %t.32.o -o %t.32
 # RUN: ld.lld -Ttext=0x10000 -section-start=.got=0x20000 --emit-relocs %t.64.o -o %t.64
-# RUN: llvm-objdump -dr %t.32 | FileCheck %s --check-prefix=RELAX
-# RUN: llvm-objdump -dr %t.64 | FileCheck %s --check-prefix=RELAX
+# RUN: llvm-objdump -dr %t.32 | FileCheck %s --check-prefixes=RELAX,RELAX32
+# RUN: llvm-objdump -dr %t.64 | FileCheck %s --check-prefixes=RELAX,RELAX64
 
 ## -r should keep original relocations.
 # RUN: ld.lld -r %t.64.o -o %t.64.r
@@ -27,10 +27,19 @@
 # RELAX-NEXT:     R_LARCH_RELAX *ABS*
 # RELAX-NEXT:     R_LARCH_PCREL20_S2 _start
 # RELAX-NEXT:     R_LARCH_RELAX *ABS*
-# RELAX-NEXT:   nop
-# RELAX-NEXT:     R_LARCH_ALIGN *ABS*+0xc
-# RELAX-NEXT:   nop
-# RELAX-NEXT:   ret
+# RELAX32-NEXT:  nop
+# RELAX32-NEXT:    R_LARCH_ALIGN *ABS*+0xc
+# RELAX32-NEXT:  nop
+# RELAX32-NEXT:  ret
+
+# RELAX64-NEXT:  bl  -8
+# RELAX64-NEXT:    R_LARCH_B26 _start
+# RELAX64-NEXT:    R_LARCH_RELAX *ABS*
+# RELAX64-NEXT:  b   -12
+# RELAX64-NEXT:    R_LARCH_B26 _start
+# RELAX64-NEXT:    R_LARCH_RELAX *ABS*
+# RELAX64-NEXT:  ret
+# RELAX64-NEXT:    R_LARCH_ALIGN *ABS*+0xc
 
 # NORELAX:      <_start>:
 # NORELAX-NEXT:   pcalau12i $a0, 0
@@ -45,6 +54,14 @@
 # NORELAX-NEXT:   ld.d      $a0, $a0, 0
 # NORELAX-NEXT:     R_LARCH_GOT_PC_LO12 _start
 # NORELAX-NEXT:     R_LARCH_RELAX *ABS*
+# NORELAX-NEXT:   pcaddu18i $ra, 0
+# NORELAX-NEXT:     R_LARCH_CALL36 _start
+# NORELAX-NEXT:     R_LARCH_RELAX *ABS*
+# NORELAX-NEXT:   jirl   $ra, $ra, -16
+# NORELAX-NEXT:   pcaddu18i $a0, 0
+# NORELAX-NEXT:     R_LARCH_CALL36 _start
+# NORELAX-NEXT:     R_LARCH_RELAX *ABS*
+# NORELAX-NEXT:   jirl $zero, $a0, -24
 # NORELAX-NEXT:   ret
 # NORELAX-NEXT:     R_LARCH_ALIGN *ABS*+0xc
 
@@ -61,6 +78,14 @@
 # CHECKR-NEXT:   ld.d      $a0, $a0, 0
 # CHECKR-NEXT:     R_LARCH_GOT_PC_LO12 _start
 # CHECKR-NEXT:     R_LARCH_RELAX *ABS*
+# CHECKR-NEXT:   pcaddu18i $ra, 0
+# CHECKR-NEXT:     R_LARCH_CALL36 _start
+# CHECKR-NEXT:     R_LARCH_RELAX *ABS*
+# CHECKR-NEXT:   jirl   $ra, $ra, 0
+# CHECKR-NEXT:   pcaddu18i $a0, 0
+# CHECKR-NEXT:     R_LARCH_CALL36 _start
+# CHECKR-NEXT:     R_LARCH_RELAX *ABS*
+# CHECKR-NEXT:   jr     $a0
 # CHECKR-NEXT:   nop
 # CHECKR-NEXT:     R_LARCH_ALIGN *ABS*+0xc
 # CHECKR-NEXT:   nop
@@ -71,5 +96,10 @@
 _start:
   la.pcrel $a0, _start
   la.got   $a0, _start
+
+.ifdef ELF64
+  call36 _start
+  tail36 $a0, _start
+.endif
   .p2align 4
   ret


        


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