[llvm] [X86] fix combineSubSetcc to handle a large constant (PR #66941)

[Matheus Izvekov via llvm-commits]

https://github.com/mizvekov created https://github.com/llvm/llvm-project/pull/66941

None

>From 148444441d998a1ea86c91e1d428e0ca3289200b Mon Sep 17 00:00:00 2001
From: Matheus Izvekov <mizvekov at gmail.com>
Date: Wed, 20 Sep 2023 20:43:06 +0200
Subject: [PATCH] [X86] fix combineSubSetcc to handle a large constant

---
 llvm/lib/Target/X86/X86ISelLowering.cpp    |  2 +-
 llvm/test/CodeGen/X86/select_const_i128.ll | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/X86/select_const_i128.ll

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 5d5040e8bac5bb1..81aa998d33c639b 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -54221,7 +54221,7 @@ static SDValue combineSubSetcc(SDNode *N, SelectionDAG &DAG) {
     SDValue SetCC = Op1.getOperand(0);
     X86::CondCode CC = (X86::CondCode)SetCC.getConstantOperandVal(0);
     X86::CondCode NewCC = X86::GetOppositeBranchCondition(CC);
-    uint64_t NewImm = Op0C->getZExtValue() - 1;
+    APInt NewImm = Op0C->getAPIntValue() - 1;
     SDLoc DL(Op1);
     SDValue NewSetCC = getSETCC(NewCC, SetCC.getOperand(1), DL, DAG);
     NewSetCC = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, NewSetCC);
diff --git a/llvm/test/CodeGen/X86/select_const_i128.ll b/llvm/test/CodeGen/X86/select_const_i128.ll
new file mode 100644
index 000000000000000..af38bd6ce9e3eff
--- /dev/null
+++ b/llvm/test/CodeGen/X86/select_const_i128.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 3
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mcpu=x86-64-v2 | FileCheck %s
+
+define i128 @select_eq_i128(ptr %a) {
+; CHECK-LABEL: select_eq_i128:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movdqa (%rdi), %xmm0
+; CHECK-NEXT:    pxor {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    ptest %xmm0, %xmm0
+; CHECK-NEXT:    setne %al
+; CHECK-NEXT:    xorl %ecx, %ecx
+; CHECK-NEXT:    addq $-1, %rax
+; CHECK-NEXT:    movabsq $9223372036854775807, %rdx # imm = 0x7FFFFFFFFFFFFFFF
+; CHECK-NEXT:    adcq %rcx, %rdx
+; CHECK-NEXT:    retq
+  %1 = load i128, ptr %a, align 16
+  %cmp = icmp eq i128 %1, 1
+  %cond = select i1 %cmp, i128 170141183460469231731687303715884105727, i128 -170141183460469231731687303715884105728
+  ret i128 %cond
+}