[llvm] [AMDGPU][SplitModule] Fix potential divide by zero (PR #117602)

[Fraser Cormack via llvm-commits]

https://github.com/frasercrmck created https://github.com/llvm/llvm-project/pull/117602

A static analysis tool found that ModuleCost could be zero, so would perform divide by zero when being printed. Perhaps this is unreachable in practice, but the fix is straightforward enough and unlikely to be a performance concern.

>From 292003042995cfe72b13626ecc58e7e88e650897 Mon Sep 17 00:00:00 2001
From: Fraser Cormack <fraser at codeplay.com>
Date: Mon, 25 Nov 2024 18:16:29 +0000
Subject: [PATCH] [AMDGPU][SplitModule] Fix potential divide by zero

A static analysis tool found that ModuleCost could be zero, so would
perform divide by zero when being printed. Perhaps this is unreachable
in practice, but the fix is straightforward enough and unlikely to be a
performance concern.
---
 llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
index 5d7aff1c5092cc..3b6c2cbe390ed2 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
@@ -149,7 +149,8 @@ static constexpr unsigned InvalidPID = -1;
 /// \param Dem denominator
 /// \returns a printable object to print (Num/Dem) using "%0.2f".
 static auto formatRatioOf(CostType Num, CostType Dem) {
-  return format("%0.2f", (static_cast<double>(Num) / Dem) * 100);
+  CostType DemOr1 = Dem ? Dem : 1;
+  return format("%0.2f", (static_cast<double>(Num) / DemOr1) * 100);
 }
 
 /// Checks whether a given function is non-copyable.