From 4b702946006cfa9be9ab646ce5fc5b25248edd81 Mon Sep 17 00:00:00 2001
From: hev <wangrui@loongson.cn>
Date: Thu, 6 Jun 2024 09:44:08 +0800
Subject: [PATCH] [LoongArch] Add a hook to sign extend i32 ConstantInt
 operands of phis on LA64 (#93813)

Materializing constants on LoongArch is simpler if the constant is sign
extended from i32. By default i32 constant operands of phis are zero
extended.

This patch adds a hook to allow LoongArch to override this for i32. We
have an existing isSExtCheaperThanZExt, but it operates on EVT which we
don't have at these places in the code.
---
 .../LoongArch/LoongArchISelLowering.cpp       |  4 +++
 .../Target/LoongArch/LoongArchISelLowering.h  |  1 +
 llvm/test/CodeGen/LoongArch/sextw-removal.ll  | 32 ++++++-------------
 3 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index 51384f25d24551..32e02e3ee8f541 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -5004,6 +5004,10 @@ bool LoongArchTargetLowering::isSExtCheaperThanZExt(EVT SrcVT,
   return Subtarget.is64Bit() && SrcVT == MVT::i32 && DstVT == MVT::i64;
 }
 
+bool LoongArchTargetLowering::signExtendConstant(const ConstantInt *CI) const {
+  return Subtarget.is64Bit() && CI->getType()->isIntegerTy(32);
+}
+
 bool LoongArchTargetLowering::hasAndNotCompare(SDValue Y) const {
   // TODO: Support vectors.
   if (Y.getValueType().isVector())
diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.h b/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
index f274b1971fd232..9328831a17a30d 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.h
@@ -229,6 +229,7 @@ class LoongArchTargetLowering : public TargetLowering {
   bool isLegalAddImmediate(int64_t Imm) const override;
   bool isZExtFree(SDValue Val, EVT VT2) const override;
   bool isSExtCheaperThanZExt(EVT SrcVT, EVT DstVT) const override;
+  bool signExtendConstant(const ConstantInt *CI) const override;
 
   bool hasAndNotCompare(SDValue Y) const override;
 
diff --git a/llvm/test/CodeGen/LoongArch/sextw-removal.ll b/llvm/test/CodeGen/LoongArch/sextw-removal.ll
index 502b6cf88099e4..ba889fc8393b4a 100644
--- a/llvm/test/CodeGen/LoongArch/sextw-removal.ll
+++ b/llvm/test/CodeGen/LoongArch/sextw-removal.ll
@@ -762,7 +762,6 @@ define signext i32 @test14(i32 signext %0, i32 signext %1) {
 ; CHECK-NEXT:  # %bb.1: # %.preheader
 ; CHECK-NEXT:    ori $a3, $zero, 1
 ; CHECK-NEXT:    addi.w $a2, $zero, -1
-; CHECK-NEXT:    lu32i.d $a2, 0
 ; CHECK-NEXT:    ori $a4, $zero, 1000
 ; CHECK-NEXT:    .p2align 4, , 16
 ; CHECK-NEXT:  .LBB13_2: # =>This Inner Loop Header: Depth=1
@@ -772,10 +771,9 @@ define signext i32 @test14(i32 signext %0, i32 signext %1) {
 ; CHECK-NEXT:    addi.w $a3, $a3, 1
 ; CHECK-NEXT:    blt $a3, $a1, .LBB13_2
 ; CHECK-NEXT:  .LBB13_4:
-; CHECK-NEXT:    addi.w $a0, $a0, 0
 ; CHECK-NEXT:    ret
 ; CHECK-NEXT:  .LBB13_5:
-; CHECK-NEXT:    addi.w $a0, $a2, 0
+; CHECK-NEXT:    move $a0, $a2
 ; CHECK-NEXT:    ret
 ;
 ; NORMV-LABEL: test14:
@@ -785,7 +783,6 @@ define signext i32 @test14(i32 signext %0, i32 signext %1) {
 ; NORMV-NEXT:  # %bb.1: # %.preheader
 ; NORMV-NEXT:    ori $a3, $zero, 1
 ; NORMV-NEXT:    addi.w $a2, $zero, -1
-; NORMV-NEXT:    lu32i.d $a2, 0
 ; NORMV-NEXT:    ori $a4, $zero, 1000
 ; NORMV-NEXT:    .p2align 4, , 16
 ; NORMV-NEXT:  .LBB13_2: # =>This Inner Loop Header: Depth=1
@@ -795,13 +792,12 @@ define signext i32 @test14(i32 signext %0, i32 signext %1) {
 ; NORMV-NEXT:    add.d $a0, $a3, $a0
 ; NORMV-NEXT:    addi.d $a3, $a3, 1
 ; NORMV-NEXT:    addi.w $a3, $a3, 0
-; NORMV-NEXT:    addi.d $a0, $a0, 0
+; NORMV-NEXT:    addi.w $a0, $a0, 0
 ; NORMV-NEXT:    blt $a3, $a1, .LBB13_2
 ; NORMV-NEXT:  .LBB13_4:
-; NORMV-NEXT:    addi.w $a0, $a0, 0
 ; NORMV-NEXT:    ret
 ; NORMV-NEXT:  .LBB13_5:
-; NORMV-NEXT:    addi.w $a0, $a2, 0
+; NORMV-NEXT:    move $a0, $a2
 ; NORMV-NEXT:    ret
   %3 = icmp sgt i32 %1, 1
   br i1 %3, label %4, label %12
@@ -830,8 +826,7 @@ define signext i32 @test14b(i32 %0, i32 signext %1) {
 ; CHECK-NEXT:    blt $a1, $a2, .LBB14_4
 ; CHECK-NEXT:  # %bb.1: # %.preheader
 ; CHECK-NEXT:    ori $a3, $zero, 1
-; CHECK-NEXT:    addi.w $a2, $zero, -1
-; CHECK-NEXT:    lu32i.d $a2, 0
+; CHECK-NEXT:    addi.d $a2, $zero, -1
 ; CHECK-NEXT:    ori $a4, $zero, 1000
 ; CHECK-NEXT:    .p2align 4, , 16
 ; CHECK-NEXT:  .LBB14_2: # =>This Inner Loop Header: Depth=1
@@ -854,8 +849,7 @@ define signext i32 @test14b(i32 %0, i32 signext %1) {
 ; NORMV-NEXT:    blt $a1, $a2, .LBB14_4
 ; NORMV-NEXT:  # %bb.1: # %.preheader
 ; NORMV-NEXT:    ori $a3, $zero, 1
-; NORMV-NEXT:    addi.w $a2, $zero, -1
-; NORMV-NEXT:    lu32i.d $a2, 0
+; NORMV-NEXT:    addi.d $a2, $zero, -1
 ; NORMV-NEXT:    ori $a4, $zero, 1000
 ; NORMV-NEXT:    .p2align 4, , 16
 ; NORMV-NEXT:  .LBB14_2: # =>This Inner Loop Header: Depth=1
@@ -900,8 +894,7 @@ define signext i32 @test14c(i32 zeroext %0, i32 signext %1) {
 ; CHECK-NEXT:    blt $a1, $a2, .LBB15_4
 ; CHECK-NEXT:  # %bb.1: # %.preheader
 ; CHECK-NEXT:    ori $a3, $zero, 1
-; CHECK-NEXT:    addi.w $a2, $zero, -1
-; CHECK-NEXT:    lu32i.d $a2, 0
+; CHECK-NEXT:    addi.d $a2, $zero, -1
 ; CHECK-NEXT:    ori $a4, $zero, 1000
 ; CHECK-NEXT:    .p2align 4, , 16
 ; CHECK-NEXT:  .LBB15_2: # =>This Inner Loop Header: Depth=1
@@ -924,8 +917,7 @@ define signext i32 @test14c(i32 zeroext %0, i32 signext %1) {
 ; NORMV-NEXT:    blt $a1, $a2, .LBB15_4
 ; NORMV-NEXT:  # %bb.1: # %.preheader
 ; NORMV-NEXT:    ori $a3, $zero, 1
-; NORMV-NEXT:    addi.w $a2, $zero, -1
-; NORMV-NEXT:    lu32i.d $a2, 0
+; NORMV-NEXT:    addi.d $a2, $zero, -1
 ; NORMV-NEXT:    ori $a4, $zero, 1000
 ; NORMV-NEXT:    .p2align 4, , 16
 ; NORMV-NEXT:  .LBB15_2: # =>This Inner Loop Header: Depth=1
@@ -971,7 +963,6 @@ define signext i32 @test14d(i31 zeroext %0, i32 signext %1) {
 ; CHECK-NEXT:  # %bb.1: # %.preheader
 ; CHECK-NEXT:    ori $a3, $zero, 1
 ; CHECK-NEXT:    addi.w $a2, $zero, -1
-; CHECK-NEXT:    lu32i.d $a2, 0
 ; CHECK-NEXT:    ori $a4, $zero, 1000
 ; CHECK-NEXT:    .p2align 4, , 16
 ; CHECK-NEXT:  .LBB16_2: # =>This Inner Loop Header: Depth=1
@@ -981,10 +972,9 @@ define signext i32 @test14d(i31 zeroext %0, i32 signext %1) {
 ; CHECK-NEXT:    addi.w $a3, $a3, 1
 ; CHECK-NEXT:    blt $a3, $a1, .LBB16_2
 ; CHECK-NEXT:  .LBB16_4:
-; CHECK-NEXT:    addi.w $a0, $a0, 0
 ; CHECK-NEXT:    ret
 ; CHECK-NEXT:  .LBB16_5:
-; CHECK-NEXT:    addi.w $a0, $a2, 0
+; CHECK-NEXT:    move $a0, $a2
 ; CHECK-NEXT:    ret
 ;
 ; NORMV-LABEL: test14d:
@@ -994,7 +984,6 @@ define signext i32 @test14d(i31 zeroext %0, i32 signext %1) {
 ; NORMV-NEXT:  # %bb.1: # %.preheader
 ; NORMV-NEXT:    ori $a3, $zero, 1
 ; NORMV-NEXT:    addi.w $a2, $zero, -1
-; NORMV-NEXT:    lu32i.d $a2, 0
 ; NORMV-NEXT:    ori $a4, $zero, 1000
 ; NORMV-NEXT:    .p2align 4, , 16
 ; NORMV-NEXT:  .LBB16_2: # =>This Inner Loop Header: Depth=1
@@ -1004,13 +993,12 @@ define signext i32 @test14d(i31 zeroext %0, i32 signext %1) {
 ; NORMV-NEXT:    add.d $a0, $a3, $a0
 ; NORMV-NEXT:    addi.d $a3, $a3, 1
 ; NORMV-NEXT:    addi.w $a3, $a3, 0
-; NORMV-NEXT:    addi.d $a0, $a0, 0
+; NORMV-NEXT:    addi.w $a0, $a0, 0
 ; NORMV-NEXT:    blt $a3, $a1, .LBB16_2
 ; NORMV-NEXT:  .LBB16_4:
-; NORMV-NEXT:    addi.w $a0, $a0, 0
 ; NORMV-NEXT:    ret
 ; NORMV-NEXT:  .LBB16_5:
-; NORMV-NEXT:    addi.w $a0, $a2, 0
+; NORMV-NEXT:    move $a0, $a2
 ; NORMV-NEXT:    ret
   %zext = zext i31 %0 to i32
   %3 = icmp sgt i32 %1, 1