[llvm] [RISCV][llvm] Correct shamt in P extension EXTRACT_VECTOR_ELT lowering (PR #169823)
Brandon Wu via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 27 07:58:46 PST 2025
https://github.com/4vtomat created https://github.com/llvm/llvm-project/pull/169823
During operation legalization, element type should have been turn into
XLenVT which makes the SHL a no-op. We need to use exact vector element
type instead.
>From efd5e851dba16b44e1e91f0fb6fcd8c07191715f Mon Sep 17 00:00:00 2001
From: Brandon Wu <songwu0813 at gmail.com>
Date: Thu, 27 Nov 2025 04:57:42 -0800
Subject: [PATCH 1/2] pre commit test
---
llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll | 20 ++++++++++++++++++++
llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll | 10 ++++++++++
2 files changed, 30 insertions(+)
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
index d4ea9e6c3def0..59f743b8af691 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
@@ -484,6 +484,16 @@ define void @test_extract_vector_16(ptr %ret_ptr, ptr %a_ptr) {
ret void
}
+define void @test_extract_vector_16_elem1(ptr %ret_ptr, ptr %a_ptr) {
+; CHECK-LABEL: test_extract_vector_16_elem1:
+; CHECK: # %bb.0:
+; CHECK-NEXT: ret
+ %a = load <2 x i16>, ptr %a_ptr
+ %extracted = extractelement <2 x i16> %a, i32 1
+ store i16 %extracted, ptr %ret_ptr
+ ret void
+}
+
define void @test_extract_vector_8(ptr %ret_ptr, ptr %a_ptr) {
; CHECK-LABEL: test_extract_vector_8:
; CHECK: # %bb.0:
@@ -496,6 +506,16 @@ define void @test_extract_vector_8(ptr %ret_ptr, ptr %a_ptr) {
ret void
}
+define void @test_extract_vector_8_elem1(ptr %ret_ptr, ptr %a_ptr) {
+; CHECK-LABEL: test_extract_vector_8_elem1:
+; CHECK: # %bb.0:
+; CHECK-NEXT: ret
+ %a = load <4 x i8>, ptr %a_ptr
+ %extracted = extractelement <4 x i8> %a, i32 1
+ store i8 %extracted, ptr %ret_ptr
+ ret void
+}
+
; Test for splat
define void @test_non_const_splat_i8(ptr %ret_ptr, ptr %a_ptr, i8 %elt) {
; CHECK-LABEL: test_non_const_splat_i8:
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
index b39b807d43154..e0acf4d0dd96b 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
@@ -495,6 +495,16 @@ define void @test_extract_vector_32(ptr %ret_ptr, ptr %a_ptr) {
ret void
}
+define void @test_extract_vector_32_elem1(ptr %ret_ptr, ptr %a_ptr) {
+; CHECK-LABEL: test_extract_vector_32_elem1:
+; CHECK: # %bb.0:
+; CHECK-NEXT: ret
+ %a = load <2 x i32>, ptr %a_ptr
+ %extracted = extractelement <2 x i32> %a, i32 1
+ store i32 %extracted, ptr %ret_ptr
+ ret void
+}
+
; Test basic add/sub operations for v2i32 (RV64 only)
define void @test_padd_w(ptr %ret_ptr, ptr %a_ptr, ptr %b_ptr) {
; CHECK-LABEL: test_padd_w:
>From 1f918c925aa072f5835a8a723e3ded7aa90e76cd Mon Sep 17 00:00:00 2001
From: Brandon Wu <songwu0813 at gmail.com>
Date: Thu, 27 Nov 2025 07:55:02 -0800
Subject: [PATCH 2/2] [RISCV][llvm] Correct shamt in P extension
EXTRACT_VECTOR_ELT lowering
During operation legalization, element type should have been turn into
XLenVT which makes the SHL a no-op. We need to use exact vector element
type instead.
---
llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 2 +-
llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll | 18 +++++++++++++++---
llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll | 2 ++
3 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index be53f51afe79f..0d9b8bddbcc8f 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -10699,7 +10699,7 @@ SDValue RISCVTargetLowering::lowerEXTRACT_VECTOR_ELT(SDValue Op,
VecVT != MVT::v4i8 && VecVT != MVT::v2i32)
return SDValue();
SDValue Extracted = DAG.getBitcast(XLenVT, Vec);
- unsigned ElemWidth = EltVT.getSizeInBits();
+ unsigned ElemWidth = VecVT.getVectorElementType().getSizeInBits();
SDValue Shamt = DAG.getNode(ISD::MUL, DL, XLenVT, Idx,
DAG.getConstant(ElemWidth, DL, XLenVT));
return DAG.getNode(ISD::SRL, DL, XLenVT, Extracted, Shamt);
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
index 59f743b8af691..f803f6aa09652 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
@@ -485,9 +485,18 @@ define void @test_extract_vector_16(ptr %ret_ptr, ptr %a_ptr) {
}
define void @test_extract_vector_16_elem1(ptr %ret_ptr, ptr %a_ptr) {
-; CHECK-LABEL: test_extract_vector_16_elem1:
-; CHECK: # %bb.0:
-; CHECK-NEXT: ret
+; CHECK-RV32-LABEL: test_extract_vector_16_elem1:
+; CHECK-RV32: # %bb.0:
+; CHECK-RV32-NEXT: lhu a1, 2(a1)
+; CHECK-RV32-NEXT: sh a1, 0(a0)
+; CHECK-RV32-NEXT: ret
+;
+; CHECK-RV64-LABEL: test_extract_vector_16_elem1:
+; CHECK-RV64: # %bb.0:
+; CHECK-RV64-NEXT: lw a1, 0(a1)
+; CHECK-RV64-NEXT: srli a1, a1, 16
+; CHECK-RV64-NEXT: sh a1, 0(a0)
+; CHECK-RV64-NEXT: ret
%a = load <2 x i16>, ptr %a_ptr
%extracted = extractelement <2 x i16> %a, i32 1
store i16 %extracted, ptr %ret_ptr
@@ -509,6 +518,9 @@ define void @test_extract_vector_8(ptr %ret_ptr, ptr %a_ptr) {
define void @test_extract_vector_8_elem1(ptr %ret_ptr, ptr %a_ptr) {
; CHECK-LABEL: test_extract_vector_8_elem1:
; CHECK: # %bb.0:
+; CHECK-NEXT: lw a1, 0(a1)
+; CHECK-NEXT: srli a1, a1, 8
+; CHECK-NEXT: sb a1, 0(a0)
; CHECK-NEXT: ret
%a = load <4 x i8>, ptr %a_ptr
%extracted = extractelement <4 x i8> %a, i32 1
diff --git a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
index e0acf4d0dd96b..9b021df8dd452 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
@@ -498,6 +498,8 @@ define void @test_extract_vector_32(ptr %ret_ptr, ptr %a_ptr) {
define void @test_extract_vector_32_elem1(ptr %ret_ptr, ptr %a_ptr) {
; CHECK-LABEL: test_extract_vector_32_elem1:
; CHECK: # %bb.0:
+; CHECK-NEXT: lw a1, 4(a1)
+; CHECK-NEXT: sw a1, 0(a0)
; CHECK-NEXT: ret
%a = load <2 x i32>, ptr %a_ptr
%extracted = extractelement <2 x i32> %a, i32 1
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