[llvm] [RISCV] Use QC_E_ADDI while eliminating the frameindex (PR #139515)
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Mon May 12 02:10:34 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-risc-v
Author: Sudharsan Veeravalli (svs-quic)
<details>
<summary>Changes</summary>
The QC_E_ADDI instruction from the Xqcilia extension takes a signed 26-bit immediate and can be used instead of splitting the offset across two ADDI's while eliminating the frameindex.
---
Full diff: https://github.com/llvm/llvm-project/pull/139515.diff
2 Files Affected:
- (modified) llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp (+11)
- (modified) llvm/test/CodeGen/RISCV/stack-offset.ll (+99)
``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
index c6f6c9007b2b1..8c754222a3b0c 100644
--- a/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
+++ b/llvm/lib/Target/RISCV/RISCVRegisterInfo.cpp
@@ -288,6 +288,17 @@ void RISCVRegisterInfo::adjustReg(MachineBasicBlock &MBB,
return;
}
+ // Use the QC_E_ADDI instruction from the Xqcilia extension that can take a
+ // signed 26-bit immediate. Avoid anything which can be done with a single lui
+ // as it might be compressible.
+ if (ST.hasVendorXqcilia() && isInt<26>(Val) && (Val & 0xFFF) != 0) {
+ BuildMI(MBB, II, DL, TII->get(RISCV::QC_E_ADDI), DestReg)
+ .addReg(SrcReg, getKillRegState(KillSrcReg))
+ .addImm(Val)
+ .setMIFlag(Flag);
+ return;
+ }
+
// Try to split the offset across two ADDIs. We need to keep the intermediate
// result aligned after each ADDI. We need to determine the maximum value we
// can put in each ADDI. In the negative direction, we can use -2048 which is
diff --git a/llvm/test/CodeGen/RISCV/stack-offset.ll b/llvm/test/CodeGen/RISCV/stack-offset.ll
index 402d3546eae29..cdc117675af97 100644
--- a/llvm/test/CodeGen/RISCV/stack-offset.ll
+++ b/llvm/test/CodeGen/RISCV/stack-offset.ll
@@ -1,6 +1,8 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
; RUN: | FileCheck %s -check-prefixes=RV32,RV32I
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs -mattr=+experimental-xqcilia < %s \
+; RUN: | FileCheck %s -check-prefixes=RV32XQCILIA
; RUN: llc -mtriple=riscv32 -verify-machineinstrs -mattr=+zba < %s \
; RUN: | FileCheck %s -check-prefixes=RV32,RV32ZBA
; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
@@ -39,6 +41,27 @@ define void @test() {
; RV32I-NEXT: .cfi_def_cfa_offset 0
; RV32I-NEXT: ret
;
+; RV32XQCILIA-LABEL: test:
+; RV32XQCILIA: # %bb.0:
+; RV32XQCILIA-NEXT: addi sp, sp, -2032
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 2032
+; RV32XQCILIA-NEXT: sw ra, 2028(sp) # 4-byte Folded Spill
+; RV32XQCILIA-NEXT: .cfi_offset ra, -4
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, -3168
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 5200
+; RV32XQCILIA-NEXT: addi a0, sp, 12
+; RV32XQCILIA-NEXT: qc.e.addi a1, sp, 2060
+; RV32XQCILIA-NEXT: qc.e.addi a2, sp, 4108
+; RV32XQCILIA-NEXT: qc.e.addi a3, sp, 5132
+; RV32XQCILIA-NEXT: call inspect
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, 3168
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 2032
+; RV32XQCILIA-NEXT: lw ra, 2028(sp) # 4-byte Folded Reload
+; RV32XQCILIA-NEXT: .cfi_restore ra
+; RV32XQCILIA-NEXT: addi sp, sp, 2032
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 0
+; RV32XQCILIA-NEXT: ret
+;
; RV32ZBA-LABEL: test:
; RV32ZBA: # %bb.0:
; RV32ZBA-NEXT: addi sp, sp, -2032
@@ -150,6 +173,25 @@ define void @align_8() {
; RV32I-NEXT: .cfi_def_cfa_offset 0
; RV32I-NEXT: ret
;
+; RV32XQCILIA-LABEL: align_8:
+; RV32XQCILIA: # %bb.0:
+; RV32XQCILIA-NEXT: addi sp, sp, -256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: sw ra, 252(sp) # 4-byte Folded Spill
+; RV32XQCILIA-NEXT: .cfi_offset ra, -4
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, -3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 4112
+; RV32XQCILIA-NEXT: addi a0, sp, 7
+; RV32XQCILIA-NEXT: qc.e.addi a1, sp, 4104
+; RV32XQCILIA-NEXT: call inspect
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, 3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: lw ra, 252(sp) # 4-byte Folded Reload
+; RV32XQCILIA-NEXT: .cfi_restore ra
+; RV32XQCILIA-NEXT: addi sp, sp, 256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 0
+; RV32XQCILIA-NEXT: ret
+;
; RV32ZBA-LABEL: align_8:
; RV32ZBA: # %bb.0:
; RV32ZBA-NEXT: addi sp, sp, -2032
@@ -246,6 +288,25 @@ define void @align_4() {
; RV32I-NEXT: .cfi_def_cfa_offset 0
; RV32I-NEXT: ret
;
+; RV32XQCILIA-LABEL: align_4:
+; RV32XQCILIA: # %bb.0:
+; RV32XQCILIA-NEXT: addi sp, sp, -256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: sw ra, 252(sp) # 4-byte Folded Spill
+; RV32XQCILIA-NEXT: .cfi_offset ra, -4
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, -3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 4112
+; RV32XQCILIA-NEXT: addi a0, sp, 7
+; RV32XQCILIA-NEXT: qc.e.addi a1, sp, 4104
+; RV32XQCILIA-NEXT: call inspect
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, 3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: lw ra, 252(sp) # 4-byte Folded Reload
+; RV32XQCILIA-NEXT: .cfi_restore ra
+; RV32XQCILIA-NEXT: addi sp, sp, 256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 0
+; RV32XQCILIA-NEXT: ret
+;
; RV32ZBA-LABEL: align_4:
; RV32ZBA: # %bb.0:
; RV32ZBA-NEXT: addi sp, sp, -2032
@@ -342,6 +403,25 @@ define void @align_2() {
; RV32-NEXT: .cfi_def_cfa_offset 0
; RV32-NEXT: ret
;
+; RV32XQCILIA-LABEL: align_2:
+; RV32XQCILIA: # %bb.0:
+; RV32XQCILIA-NEXT: addi sp, sp, -256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: sw ra, 252(sp) # 4-byte Folded Spill
+; RV32XQCILIA-NEXT: .cfi_offset ra, -4
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, -3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 4112
+; RV32XQCILIA-NEXT: addi a0, sp, 9
+; RV32XQCILIA-NEXT: qc.e.addi a1, sp, 4106
+; RV32XQCILIA-NEXT: call inspect
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, 3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: lw ra, 252(sp) # 4-byte Folded Reload
+; RV32XQCILIA-NEXT: .cfi_restore ra
+; RV32XQCILIA-NEXT: addi sp, sp, 256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 0
+; RV32XQCILIA-NEXT: ret
+;
; RV64-LABEL: align_2:
; RV64: # %bb.0:
; RV64-NEXT: addi sp, sp, -2032
@@ -395,6 +475,25 @@ define void @align_1() {
; RV32-NEXT: .cfi_def_cfa_offset 0
; RV32-NEXT: ret
;
+; RV32XQCILIA-LABEL: align_1:
+; RV32XQCILIA: # %bb.0:
+; RV32XQCILIA-NEXT: addi sp, sp, -256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: sw ra, 252(sp) # 4-byte Folded Spill
+; RV32XQCILIA-NEXT: .cfi_offset ra, -4
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, -3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 4112
+; RV32XQCILIA-NEXT: addi a0, sp, 10
+; RV32XQCILIA-NEXT: qc.e.addi a1, sp, 4107
+; RV32XQCILIA-NEXT: call inspect
+; RV32XQCILIA-NEXT: qc.e.addi sp, sp, 3856
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 256
+; RV32XQCILIA-NEXT: lw ra, 252(sp) # 4-byte Folded Reload
+; RV32XQCILIA-NEXT: .cfi_restore ra
+; RV32XQCILIA-NEXT: addi sp, sp, 256
+; RV32XQCILIA-NEXT: .cfi_def_cfa_offset 0
+; RV32XQCILIA-NEXT: ret
+;
; RV64-LABEL: align_1:
; RV64: # %bb.0:
; RV64-NEXT: addi sp, sp, -2032
``````````
</details>
https://github.com/llvm/llvm-project/pull/139515
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