[Mips] Add MipsPat `(MipsGPRel tglobaladdr:$in)` to select MipsISD::GPRel TargetGlobalAddress by yingopq · Pull Request #165531 · llvm/llvm-project

yingopq · 2025-10-29T09:37:53Z

The original logic:

SelectionDAG has 17 nodes:
  t0: ch,glue = EntryToken
          t2: i64,ch = CopyFromReg t0, Register:i64 %0
        t11: i32 = truncate t2
      t14: i32 = and t11, Constant:i32<1>
        t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
      t21: i64 = add Register:i64 $gp_64, t20
        t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3]
      t18: i64 = add Register:i64 $gp_64, t16
    t7: i64 = select t14, t21, t18

When SelectionDAG process visitSELECT, would fold select(cond,
binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)).
As follows:

SelectionDAG has 16 nodes:
  t0: ch,glue = EntryToken
            t2: i64,ch = CopyFromReg t0, Register:i64 %0
          t11: i32 = truncate t2
        t14: i32 = and t11, Constant:i32<1>
        t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
        t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3]
      t22: i64 = select t14, t20, t16
    t23: i64 = add Register:i64 $gp_64, t22

Therefore, the original MipsPat add GPR64:$gp, (MipsGPRel tglobaladdr:$in) is no longer available. And there would be an assert:

ISEL: Starting selection on root node: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]
ISEL: Starting pattern match
  Initial Opcode index to 0
  Match failed at index 0
LLVM ERROR: Cannot select: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3]

So we add a new MipsPat def : MipsPat<(MipsGPRel tglobaladdr:$in), (DADDiu ZERO_64, tglobaladdr:$in)>, ISA_MIPS3, ABI_N64;
to parse MipsISD::GPRel TargetGlobalAddress.

Fix #142060.

llvmbot · 2025-10-29T09:38:26Z

@llvm/pr-subscribers-backend-mips

Author: None (yingopq)

Changes

When SelectionDAG process visitSELECT, would fold select(cond, binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)).
Therefore, the original MipsPat add GPR64:$gp, (MipsGPRel tglobaladdr:$in) is no longer available.

Full diff: https://github.com/llvm/llvm-project/pull/165531.diff

2 Files Affected:

(modified) llvm/lib/Target/Mips/MipsCondMov.td (+3)
(added) llvm/test/CodeGen/Mips/llvm-ir/select-globaladdr.ll (+22)

diff --git a/llvm/lib/Target/Mips/MipsCondMov.td b/llvm/lib/Target/Mips/MipsCondMov.td
index e9e09a188bf5b..947a52bddebb4 100644
--- a/llvm/lib/Target/Mips/MipsCondMov.td
+++ b/llvm/lib/Target/Mips/MipsCondMov.td
@@ -196,6 +196,9 @@ let AdditionalPredicates = [NotInMicroMips] in {
   }
 
   // Instantiation of conditional move patterns.
+  def : MipsPat<(add GPR64:$gp, (select GPR32:$cond, (MipsGPRel tglobaladdr:$T), (MipsGPRel tglobaladdr:$F))),
+              (MOVN_I_I64 (i64 (DADDiu GPR64:$gp, tglobaladdr:$T)), GPR32:$cond, (i64 (DADDiu GPR64:$gp, tglobaladdr:$F)))>, ISA_MIPS3, ABI_N64;
+
   defm : MovzPats0<GPR32, GPR32, MOVZ_I_I, SLT, SLTu, SLTi, SLTiu>,
          INSN_MIPS4_32_NOT_32R6_64R6;
   defm : MovzPats1<GPR32, GPR32, MOVZ_I_I, XOR>, INSN_MIPS4_32_NOT_32R6_64R6;
diff --git a/llvm/test/CodeGen/Mips/llvm-ir/select-globaladdr.ll b/llvm/test/CodeGen/Mips/llvm-ir/select-globaladdr.ll
new file mode 100644
index 0000000000000..54c272a832721
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/llvm-ir/select-globaladdr.ll
@@ -0,0 +1,22 @@
+; RUN: llc < %s -mattr +noabicalls -mgpopt | FileCheck %s -check-prefixes=MIPS64
+
+target datalayout = "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "mips64-unknown-linux-muslabi64"
+
+@.str = external constant [6 x i8]
+@.str.1 = external constant [6 x i8]
+
+define ptr @tst_select_ptr_ptr(i1 %tobool.not) {
+entry:
+; MIPS64-LABEL: tst_select_ptr_ptr:
+; MIPS64:       # %bb.0: # %entry
+; MIPS64:         sll $1, $4, 0
+; MIPS64:         andi $1, $1, 1
+; MIPS64:         daddiu $2, $gp, %gp_rel(.str)
+; MIPS64:         daddiu $3, $gp, %gp_rel(.str.1)
+; MIPS64:         jr $ra
+; MIPS64:         movn $2, $3, $1
+
+  %cond = select i1 %tobool.not, ptr @.str.1, ptr @.str
+  ret ptr %cond
+}

brad0 · 2025-11-05T03:05:18Z

@alexrp

brad0 · 2025-11-08T06:11:53Z

cc @arsenm

arsenm

It's not obvious to me what the problem being solved here is from the description. It sounds like an optimization, but when I try the test it's a selection failure. This isn't really a solution for that, you need to MipsISD::GPRel as a leaf

arsenm · 2025-11-08T06:22:47Z

Suggested change

Should remove redundant datalayout string

brad0 · 2025-11-08T06:32:53Z

It's not obvious to me what the problem being solved here is from the description.

Look at the bug report mentioned.

arsenm · 2025-11-08T06:52:45Z

It's not obvious to me what the problem being solved here is from the description.

Look at the bug report mentioned.

The commit message should directly contain all of this information

yingopq · 2025-11-12T02:33:38Z

When SelectionDAG process visitSELECT, would fold select(cond, binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)).
Therefore, the original MipsPat add GPR64:$gp, (MipsGPRel tglobaladdr:$in) is no longer available.

Sorry, I would update the commit message.

arsenm

The bigger issue is there isn't a freestanding pattern for the global address

yingopq · 2025-11-13T03:36:19Z

The bigger issue is there isn't a freestanding pattern for the global address

Please help see the new commit message. And I did not get the meanings you said.

arsenm · 2025-11-13T04:19:04Z

The bigger issue is there isn't a freestanding pattern for the global address

Please help see the new commit message. And I did not get the meanings you said.

The failure is on not handling a freestanding MipsGPRel tglobaladdr:$T. This patch is not a suitable fix for that problem. This patch can only be an optimization, which is hiding a missed pattern on the raw address materialize. If you remove the select from this, I'd expect it could still fail the same way

yingopq · 2025-11-13T08:36:27Z

The bigger issue is there isn't a freestanding pattern for the global address

Please help see the new commit message. And I did not get the meanings you said.

The failure is on not handling a freestanding MipsGPRel tglobaladdr:$T. This patch is not a suitable fix for that problem. This patch can only be an optimization, which is hiding a missed pattern on the raw address materialize. If you remove the select from this, I'd expect it could still fail the same way

I got it, thanks.
Because I did not have another solution about suppooting a freestanding pattern for the global address before, so I choose this optimization. Did you have ?
And I test the issue with this patch, it worked OK.

yingopq · 2025-12-02T09:20:29Z

@arsenm Can you review again, thanks!

yingopq · 2025-12-26T09:25:06Z

Ping.

yingopq · 2026-01-05T08:58:00Z

@arsenm Can you review again, thanks!

arsenm · 2026-01-05T10:29:57Z

Can you update the patch title and description

yingopq · 2026-01-06T02:11:08Z

Can you update the patch title and description

OK.

…Rel TargetGlobalAddress The original logic: ``` SelectionDAG has 17 nodes: t0: ch,glue = EntryToken t2: i64,ch = CopyFromReg t0, Register:i64 %0 t11: i32 = truncate t2 t14: i32 = and t11, Constant:i32<1> t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] t21: i64 = add Register:i64 $gp_64, t20 t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3] t18: i64 = add Register:i64 $gp_64, t16 t7: i64 = select t14, t21, t18 ``` When SelectionDAG process visitSELECT, would fold select(cond, binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)). As follows: ``` SelectionDAG has 16 nodes: t0: ch,glue = EntryToken t2: i64,ch = CopyFromReg t0, Register:i64 %0 t11: i32 = truncate t2 t14: i32 = and t11, Constant:i32<1> t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3] t22: i64 = select t14, t20, t16 t23: i64 = add Register:i64 $gp_64, t22 ``` Therefore, the original MipsPat `add GPR64:$gp, (MipsGPRel tglobaladdr:$in)` is no longer available. And there would be an assert: ``` ISEL: Starting selection on root node: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] ISEL: Starting pattern match Initial Opcode index to 0 Match failed at index 0 LLVM ERROR: Cannot select: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] ``` So we add a new MipsPat: `def : MipsPat<(MipsGPRel tglobaladdr:$in), (DADDiu ZERO_64, tglobaladdr:$in)>, ISA_MIPS3, ABI_N64;` to parse MipsISD::GPRel TargetGlobalAddress. Fix llvm#142060.

github-actions · 2026-01-06T03:45:16Z

🪟 Windows x64 Test Results

129121 tests passed
2842 tests skipped
1 test failed

Failed Tests

(click on a test name to see its output)

LLVM

LLVM.CodeGen/RISCV/riscv-macho.ll

Exit Code: 3221225477

Command Output (stdout):
--
# RUN: at line 1
c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=riscv32-apple-macho C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll -o - | c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\llc.exe' -mtriple=riscv32-apple-macho 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll' -o -
# note: command had no output on stdout or stderr
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\filecheck.exe' 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll'
# note: command had no output on stdout or stderr
# RUN: at line 2
c:\_work\llvm-project\llvm-project\build\bin\llc.exe -mtriple=riscv32-apple-macho -filetype=obj C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll -o C:\_work\llvm-project\llvm-project\build\test\CodeGen\RISCV\Output\riscv-macho.ll.tmp.o
# executed command: 'c:\_work\llvm-project\llvm-project\build\bin\llc.exe' -mtriple=riscv32-apple-macho -filetype=obj 'C:\_work\llvm-project\llvm-project\llvm\test\CodeGen\RISCV\riscv-macho.ll' -o 'C:\_work\llvm-project\llvm-project\build\test\CodeGen\RISCV\Output\riscv-macho.ll.tmp.o'
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
# | Stack dump:
# | 0.	Program arguments: c:\\_work\\llvm-project\\llvm-project\\build\\bin\\llc.exe -mtriple=riscv32-apple-macho -filetype=obj C:\\_work\\llvm-project\\llvm-project\\llvm\\test\\CodeGen\\RISCV\\riscv-macho.ll -o C:\\_work\\llvm-project\\llvm-project\\build\\test\\CodeGen\\RISCV\\Output\\riscv-macho.ll.tmp.o
# | Exception Code: 0xC0000005
# | #0 0x0000000000000000
# | #1 0x00007ff671121901 (c:\_work\llvm-project\llvm-project\build\bin\llc.exe+0x4c1901)
# | #2 0x00007ff671119f11 (c:\_work\llvm-project\llvm-project\build\bin\llc.exe+0x4b9f11)
# | #3 0x00007ff670c67c0c (c:\_work\llvm-project\llvm-project\build\bin\llc.exe+0x7c0c)
# | #4 0x00007ff670c64e86 (c:\_work\llvm-project\llvm-project\build\bin\llc.exe+0x4e86)
# | #5 0x00007ff675278414 (c:\_work\llvm-project\llvm-project\build\bin\llc.exe+0x4618414)
# | #6 0x00007ffdd1864cb0 (C:\Windows\System32\KERNEL32.DLL+0x14cb0)
# | #7 0x00007ffddfffedcb (C:\Windows\SYSTEM32\ntdll.dll+0x7edcb)
# `-----------------------------
# error: command failed with exit status: 0xc0000005

--

If these failures are unrelated to your changes (for example tests are broken or flaky at HEAD), please open an issue at https://github.com/llvm/llvm-project/issues and add the infrastructure label.

yingopq · 2026-01-08T08:36:13Z

Can you update the patch title and description

Can you help review again?

…PRel TargetGlobalAddress (llvm#165531) The original logic: ``` SelectionDAG has 17 nodes: t0: ch,glue = EntryToken t2: i64,ch = CopyFromReg t0, Register:i64 %0 t11: i32 = truncate t2 t14: i32 = and t11, Constant:i32<1> t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] t21: i64 = add Register:i64 $gp_64, t20 t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3] t18: i64 = add Register:i64 $gp_64, t16 t7: i64 = select t14, t21, t18 ``` When SelectionDAG process visitSELECT, would fold select(cond, binop(x, y), binop(x, z)) to binop(x, select(cond, y, z)). As follows: ``` SelectionDAG has 16 nodes: t0: ch,glue = EntryToken t2: i64,ch = CopyFromReg t0, Register:i64 %0 t11: i32 = truncate t2 t14: i32 = and t11, Constant:i32<1> t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] t16: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str> 0 [TF=3] t22: i64 = select t14, t20, t16 t23: i64 = add Register:i64 $gp_64, t22 ``` Therefore, the original MipsPat `add GPR64:$gp, (MipsGPRel tglobaladdr:$in)` is no longer available. And there would be an assert: ``` ISEL: Starting selection on root node: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] ISEL: Starting pattern match Initial Opcode index to 0 Match failed at index 0 LLVM ERROR: Cannot select: t20: i64 = MipsISD::GPRel TargetGlobalAddress:i64<ptr @.str.1> 0 [TF=3] ``` So we add a new MipsPat `def : MipsPat<(MipsGPRel tglobaladdr:$in), (DADDiu ZERO_64, tglobaladdr:$in)>, ISA_MIPS3, ABI_N64;` to parse MipsISD::GPRel TargetGlobalAddress. Fix llvm#142060.

llvmbot added the backend:MIPS label Oct 29, 2025

alexrp mentioned this pull request Nov 5, 2025

Tracking Issue: LLVM 22 ziglang/zig#24542

Closed

17 tasks

arsenm reviewed Nov 8, 2025

View reviewed changes

arsenm reviewed Nov 12, 2025

View reviewed changes

yingopq force-pushed the Fix_bug_issue_142060 branch from 5a5f0d8 to c12da8d Compare November 13, 2025 03:32

yingopq force-pushed the Fix_bug_issue_142060 branch 2 times, most recently from 5cd8861 to 804f872 Compare December 1, 2025 09:12

brad0 requested a review from arsenm December 4, 2025 00:03

yingopq force-pushed the Fix_bug_issue_142060 branch from 804f872 to 631fc2e Compare January 6, 2026 02:56

yingopq changed the title ~~[Mips] Add MipsPat add $gp, (select $cond, tglobaladdr, tglobaladdr) to parse MipsISD::GPRel TargetGlobalAddress~~ [Mips] Add MipsPat (MipsGPRel tglobaladdr:$in) to parse MipsISD::GPRel TargetGlobalAddress Jan 6, 2026

arsenm approved these changes Jan 8, 2026

View reviewed changes

arsenm changed the title ~~[Mips] Add MipsPat (MipsGPRel tglobaladdr:$in) to parse MipsISD::GPRel TargetGlobalAddress~~ [Mips] Add MipsPat (MipsGPRel tglobaladdr:$in) to select MipsISD::GPRel TargetGlobalAddress Jan 8, 2026

arsenm merged commit 15564a8 into llvm:main Jan 8, 2026
13 of 14 checks passed

Conversation

yingopq commented Oct 29, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

llvmbot commented Oct 29, 2025

Uh oh!

brad0 commented Nov 5, 2025

Uh oh!

brad0 commented Nov 8, 2025

Uh oh!

arsenm left a comment

Choose a reason for hiding this comment

Uh oh!

arsenm Nov 8, 2025

Choose a reason for hiding this comment

Uh oh!

arsenm Jan 5, 2026

Choose a reason for hiding this comment

Uh oh!

brad0 commented Nov 8, 2025

Uh oh!

arsenm commented Nov 8, 2025

Uh oh!

yingopq commented Nov 12, 2025

Uh oh!

arsenm left a comment

Choose a reason for hiding this comment

Uh oh!

yingopq commented Nov 13, 2025

Uh oh!

arsenm commented Nov 13, 2025

Uh oh!

yingopq commented Nov 13, 2025

Uh oh!

yingopq commented Dec 2, 2025

Uh oh!

yingopq commented Dec 26, 2025

Uh oh!

yingopq commented Jan 5, 2026

Uh oh!

arsenm commented Jan 5, 2026

Uh oh!

yingopq commented Jan 6, 2026

Uh oh!

github-actions Bot commented Jan 6, 2026

🪟 Windows x64 Test Results

Failed Tests

LLVM

Uh oh!

yingopq commented Jan 8, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

yingopq commented Oct 29, 2025 •

edited

Loading