From 5290f50e44b632c22800df15c691394e768796be Mon Sep 17 00:00:00 2001
From: Sebastian Neubauer <sebastian.neubauer@amd.com>
Date: Tue, 20 Oct 2020 18:23:24 +0200
Subject: [PATCH] [AMDGPU] Fix off by one in assert

D89217 did not subtract one when accessing SubRegFromChannelTable in one
place.

Differential Revision: https://reviews.llvm.org/D89804
---
 llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index c7a0121b058b..6000c8a2a7fd 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -98,9 +98,10 @@ SIRegisterInfo::SIRegisterInfo(const GCNSubtarget &ST)
       Width = SubRegFromChannelTableWidthMap[Width];
       if (Width == 0)
         continue;
-      assert((Width - 1) < SubRegFromChannelTable.size());
-      assert(Offset < SubRegFromChannelTable[Width].size());
-      SubRegFromChannelTable[Width - 1][Offset] = Idx;
+      unsigned TableIdx = Width - 1;
+      assert(TableIdx < SubRegFromChannelTable.size());
+      assert(Offset < SubRegFromChannelTable[TableIdx].size());
+      SubRegFromChannelTable[TableIdx][Offset] = Idx;
     }
   };