[llvm] [RISCV][TypePromotion] Dont generate truncs if PromotedType is greater than Source Type (PR #86941)

[Sudharsan Veeravalli via llvm-commits]

https://github.com/svs-quic updated https://github.com/llvm/llvm-project/pull/86941

>From 37ecd0e0c17eeaf34c92d2b71796431f28e3c4aa Mon Sep 17 00:00:00 2001
From: Sudharsan Veeravalli <quic_svs at quicinc.com>
Date: Thu, 28 Mar 2024 17:40:03 +0530
Subject: [PATCH] [RISCV][TypePromotion] Fix crash with rv64

---
 llvm/lib/CodeGen/TypePromotion.cpp            |  2 +-
 llvm/test/CodeGen/RISCV/rv64-typepromotion.ll | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/RISCV/rv64-typepromotion.ll

diff --git a/llvm/lib/CodeGen/TypePromotion.cpp b/llvm/lib/CodeGen/TypePromotion.cpp
index b0830308908d6e..89aea3a2916118 100644
--- a/llvm/lib/CodeGen/TypePromotion.cpp
+++ b/llvm/lib/CodeGen/TypePromotion.cpp
@@ -643,7 +643,7 @@ void IRPromoter::ConvertTruncs() {
     ConstantInt *Mask =
         ConstantInt::get(SrcTy, APInt::getMaxValue(NumBits).getZExtValue());
     Value *Masked = Builder.CreateAnd(Trunc->getOperand(0), Mask);
-    if (SrcTy != ExtTy)
+    if (SrcTy->getBitWidth() > ExtTy->getBitWidth())
       Masked = Builder.CreateTrunc(Masked, ExtTy);
 
     if (auto *I = dyn_cast<Instruction>(Masked))
diff --git a/llvm/test/CodeGen/RISCV/rv64-typepromotion.ll b/llvm/test/CodeGen/RISCV/rv64-typepromotion.ll
new file mode 100644
index 00000000000000..bee42274741ef0
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rv64-typepromotion.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -mtriple=riscv64 -passes=typepromotion -S %s | FileCheck %s
+
+; Test that this does not crash
+define i16 @test(i8 %a, i32 %b) {
+; CHECK-LABEL: define i16 @test(
+; CHECK-SAME: i8 [[A:%.*]], i32 [[B:%.*]]) {
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = zext i8 [[A]] to i32
+; CHECK-NEXT:    [[CONV31_I1161_I:%.*]] = trunc i32 [[B]] to i16
+; CHECK-NEXT:    [[TMP1:%.*]] = zext i16 [[CONV31_I1161_I]] to i64
+; CHECK-NEXT:    [[CMP_I_I_I1163_I:%.*]] = icmp eq i64 [[TMP1]], 0
+; CHECK-NEXT:    [[TMP5:%.*]] = and i32 [[TMP0]], 255
+; CHECK-NEXT:    [[TMP3:%.*]] = zext i32 [[TMP5]] to i64
+; CHECK-NEXT:    [[TMP4:%.*]] = xor i64 [[TMP3]], [[TMP1]]
+; CHECK-NEXT:    [[TMP2:%.*]] = trunc i64 [[TMP4]] to i16
+; CHECK-NEXT:    ret i16 [[TMP2]]
+;
+entry:
+  %0 = zext i8 %a to i32
+  %conv31.i1161.i = trunc i32 %b to i16
+  %cmp.i.i.i1163.i = icmp eq i16 %conv31.i1161.i, 0
+  %rem.i.i69.rhs.trunc.i1165.i = trunc i32 %0 to i8
+  %1 = zext i8 %rem.i.i69.rhs.trunc.i1165.i to i16
+  %2 = xor i16 %1, %conv31.i1161.i
+  ret i16 %2
+}