[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER #89960

dtcxzyw · 2024-04-24T17:44:14Z

This patch supports G_CONSTANT_FOLD_BARRIER on RISCV to generate the following inst seq without crash:

define i64 @xor_and_i64(i64 %x) {
entry:
  %y = and i64 %x, 16383
  %z = xor i64 %y, 16368
  ret i64 %z
}

I don't know how to avoid creating G_CONSTANT_FOLD_BARRIER with s64 on rv32 :(

llvmbot · 2024-04-24T17:44:46Z

@llvm/pr-subscribers-llvm-globalisel

@llvm/pr-subscribers-backend-risc-v

Author: Yingwei Zheng (dtcxzyw)

Changes

This patch supports G_CONSTANT_FOLD_BARRIER on RISCV to generate the following inst seq without crash:

define i64 @<!-- -->xor_and_i64(i64 %x) {
entry:
  %y = and i64 %x, 16383
  %z = xor i64 %y, 16368
  ret i64 %z
}

I don't know how to avoid creating G_CONSTANT_FOLD_BARRIER with s64 on rv32 :(

Full diff: https://github.com/llvm/llvm-project/pull/89960.diff

3 Files Affected:

(modified) llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp (+1-1)
(added) llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv32.mir (+31)
(added) llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv64.mir (+64)

diff --git a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
index 38c1f9868d7dbe..adc68e9ee4a89b 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
@@ -227,7 +227,7 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
   ConstantActions.widenScalarToNextPow2(0).clampScalar(0, s32, sXLen);
 
   // TODO: transform illegal vector types into legal vector type
-  getActionDefinitionsBuilder(G_IMPLICIT_DEF)
+  getActionDefinitionsBuilder({G_IMPLICIT_DEF, G_CONSTANT_FOLD_BARRIER})
       .legalFor({s32, sXLen, p0})
       .legalIf(typeIsLegalBoolVec(0, BoolVecTys, ST))
       .legalIf(typeIsLegalIntOrFPVec(0, IntOrFPVecTys, ST))
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv32.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv32.mir
new file mode 100644
index 00000000000000..5d9da732b63177
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv32.mir
@@ -0,0 +1,31 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -mtriple=riscv32 -run-pass=legalizer %s -o - | FileCheck %s
+---
+name:            xor_and_i32
+body:             |
+  bb.1.entry:
+    liveins: $x10
+
+    ; CHECK-LABEL: name: xor_and_i32
+    ; CHECK: liveins: $x10
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16368
+    ; CHECK-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 15
+    ; CHECK-NEXT: [[CONSTANT_FOLD_BARRIER:%[0-9]+]]:_(s32) = G_CONSTANT_FOLD_BARRIER [[C]]
+    ; CHECK-NEXT: [[ADD:%[0-9]+]]:_(s32) = G_ADD [[CONSTANT_FOLD_BARRIER]], [[C1]]
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:_(s32) = G_AND [[COPY]], [[ADD]]
+    ; CHECK-NEXT: [[XOR:%[0-9]+]]:_(s32) = G_XOR [[AND]], [[CONSTANT_FOLD_BARRIER]]
+    ; CHECK-NEXT: $x10 = COPY [[XOR]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $x10
+    %1:_(s32) = G_CONSTANT i32 16368
+    %3:_(s32) = G_CONSTANT i32 15
+    %2:_(s32) = G_CONSTANT_FOLD_BARRIER %1
+    %4:_(s32) = G_ADD %2, %3
+    %5:_(s32) = G_AND %0, %4
+    %6:_(s32) = G_XOR %5, %2
+    $x10 = COPY %6(s32)
+    PseudoRET implicit $x10
+
+...
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv64.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv64.mir
new file mode 100644
index 00000000000000..2b4bb7eec54f8c
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv64.mir
@@ -0,0 +1,64 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 4
+# RUN: llc -mtriple=riscv64 -run-pass=legalizer %s -o - | FileCheck %s
+---
+name:            xor_and_i32
+body:             |
+  bb.1.entry:
+    liveins: $x10
+
+    ; CHECK-LABEL: name: xor_and_i32
+    ; CHECK: liveins: $x10
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x10
+    ; CHECK-NEXT: [[TRUNC:%[0-9]+]]:_(s32) = G_TRUNC [[COPY]](s64)
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 16368
+    ; CHECK-NEXT: [[C1:%[0-9]+]]:_(s32) = G_CONSTANT i32 15
+    ; CHECK-NEXT: [[CONSTANT_FOLD_BARRIER:%[0-9]+]]:_(s32) = G_CONSTANT_FOLD_BARRIER [[C]]
+    ; CHECK-NEXT: [[ADD:%[0-9]+]]:_(s32) = G_ADD [[CONSTANT_FOLD_BARRIER]], [[C1]]
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:_(s32) = G_AND [[TRUNC]], [[ADD]]
+    ; CHECK-NEXT: [[XOR:%[0-9]+]]:_(s32) = G_XOR [[AND]], [[CONSTANT_FOLD_BARRIER]]
+    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:_(s64) = G_ANYEXT [[XOR]](s32)
+    ; CHECK-NEXT: $x10 = COPY [[ANYEXT]](s64)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %1:_(s64) = COPY $x10
+    %0:_(s32) = G_TRUNC %1(s64)
+    %2:_(s32) = G_CONSTANT i32 16368
+    %4:_(s32) = G_CONSTANT i32 15
+    %3:_(s32) = G_CONSTANT_FOLD_BARRIER %2
+    %5:_(s32) = G_ADD %3, %4
+    %6:_(s32) = G_AND %0, %5
+    %7:_(s32) = G_XOR %6, %3
+    %8:_(s64) = G_ANYEXT %7(s32)
+    $x10 = COPY %8(s64)
+    PseudoRET implicit $x10
+
+...
+---
+name:            xor_and_i64
+body:             |
+  bb.1.entry:
+    liveins: $x10
+
+    ; CHECK-LABEL: name: xor_and_i64
+    ; CHECK: liveins: $x10
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x10
+    ; CHECK-NEXT: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 16368
+    ; CHECK-NEXT: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 15
+    ; CHECK-NEXT: [[CONSTANT_FOLD_BARRIER:%[0-9]+]]:_(s64) = G_CONSTANT_FOLD_BARRIER [[C]]
+    ; CHECK-NEXT: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[CONSTANT_FOLD_BARRIER]], [[C1]]
+    ; CHECK-NEXT: [[AND:%[0-9]+]]:_(s64) = G_AND [[COPY]], [[ADD]]
+    ; CHECK-NEXT: [[XOR:%[0-9]+]]:_(s64) = G_XOR [[AND]], [[CONSTANT_FOLD_BARRIER]]
+    ; CHECK-NEXT: $x10 = COPY [[XOR]](s64)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s64) = COPY $x10
+    %1:_(s64) = G_CONSTANT i64 16368
+    %3:_(s64) = G_CONSTANT i64 15
+    %2:_(s64) = G_CONSTANT_FOLD_BARRIER %1
+    %4:_(s64) = G_ADD %2, %3
+    %5:_(s64) = G_AND %0, %4
+    %6:_(s64) = G_XOR %5, %2
+    $x10 = COPY %6(s64)
+    PseudoRET implicit $x10
+
+...

llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-constbarrier-rv32.mir

michaelmaitland

Do you plan on doing regbankselect and instructionselect in a different patch?

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

michaelmaitland · 2024-05-06T13:26:27Z

Do you know why the G_CONSTANT_FOLD_BARRIER was created in the first place?

topperc · 2024-05-06T16:08:27Z

Do you know why the G_CONSTANT_FOLD_BARRIER was created in the first place?

I think it is created for constants hoisted by the ConstantHoisting pass.

dtcxzyw · 2024-05-18T03:08:29Z

Do you plan on doing regbankselect and instructionselect in a different patch?

No. X86 and AArch64 backends only mark G_CONSTANT_FOLD_BARRIER as legalized. I believe regbankselect and instructionselect for this node have been handled by the generic GISel logic.

…92ea49b6b Local branch amd-gfx 7a792ea Merged main:7b977e0f644c43232732e149b03d41de321d804e into amd-gfx:663bb9b5575a Remote branch main 9940620 [GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER (llvm#89960)

This patch supports `G_CONSTANT_FOLD_BARRIER` on RISCV to generate the following inst seq without crash: ``` define i64 @xor_and_i64(i64 %x) { entry: %y = and i64 %x, 16383 %z = xor i64 %y, 16368 ret i64 %z } ```

[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER

80a7f64

dtcxzyw requested review from michaelmaitland, mgudim and topperc April 24, 2024 17:44

llvmbot added backend:RISC-V llvm:globalisel labels Apr 24, 2024

arsenm reviewed Apr 24, 2024

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michaelmaitland reviewed May 6, 2024

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llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp Show resolved Hide resolved

[RISCV][GISel] Add more tests. NFC.

4b5ee9b

arsenm approved these changes May 18, 2024

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dtcxzyw merged commit 9940620 into llvm:main May 19, 2024
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dtcxzyw deleted the gisel-legalize-constbarrier branch May 19, 2024 08:08

PeddleSpam mentioned this pull request May 20, 2024

[AMDGPU] Fix error in #88512. #92770

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[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER #89960

[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER #89960

dtcxzyw commented Apr 24, 2024

llvmbot commented Apr 24, 2024 •

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dtcxzyw commented May 18, 2024

[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER #89960

[GISel][RISCV] Legalize G_CONSTANT_FOLD_BARRIER #89960

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