[llvm] e218140 - [RISCV][llvm] Correct shamt in P extension EXTRACT_VECTOR_ELT lowering (#169823)

[via llvm-commits]

Author: Brandon Wu
Date: 2025-12-01T11:03:50+08:00
New Revision: e2181400d70857bc5a212a4053d5d7940c84acaf

URL: https://github.com/llvm/llvm-project/commit/e2181400d70857bc5a212a4053d5d7940c84acaf
DIFF: https://github.com/llvm/llvm-project/commit/e2181400d70857bc5a212a4053d5d7940c84acaf.diff

LOG: [RISCV][llvm] Correct shamt in P extension EXTRACT_VECTOR_ELT lowering (#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.

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVISelLowering.cpp
    llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
    llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index d2e4bb4199a7a..a6212f5cc84be 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -10743,7 +10743,7 @@ 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 d4ea9e6c3def0..f803f6aa09652 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv32.ll
@@ -484,6 +484,25 @@ 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-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
+  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 +515,19 @@ 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:    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
+  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..9b021df8dd452 100644
--- a/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
+++ b/llvm/test/CodeGen/RISCV/rvp-ext-rv64.ll
@@ -495,6 +495,18 @@ 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:    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
+  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: