[llvm] [AMDGPU][SplitModule] Fix unintentional integer division (PR #117586)

[Fraser Cormack via llvm-commits]

https://github.com/frasercrmck updated https://github.com/llvm/llvm-project/pull/117586

>From 36267e14d049484f1cd8847182df738eaddd310f Mon Sep 17 00:00:00 2001
From: Fraser Cormack <fraser at codeplay.com>
Date: Mon, 25 Nov 2024 17:56:50 +0000
Subject: [PATCH] [AMDGPU][SplitModule] Fix unintentional integer division

A static analysis tool warned that a division was always being performed
in integer division, so was either 0.0 or 1.0. This doesn't seem
intentional, so has been fixed to return a true ratio using
floating-point division. This has a knock-on effect on how a test was
splitting modules.
---
 llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp        |  2 +-
 .../llvm-split/AMDGPU/large-kernels-merging.ll      | 13 +++++++------
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
index 5d7aff1c5092cc..55804ceaa50ca1 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
@@ -1101,7 +1101,7 @@ void RecursiveSearchSplitting::pickPartition(unsigned Depth, unsigned Idx,
         // Check if the amount of code in common makes it worth it.
         assert(SimilarDepsCost && Entry.CostExcludingGraphEntryPoints);
         const double Ratio =
-            SimilarDepsCost / Entry.CostExcludingGraphEntryPoints;
+            (double)SimilarDepsCost / Entry.CostExcludingGraphEntryPoints;
         assert(Ratio >= 0.0 && Ratio <= 1.0);
         if (LargeFnOverlapForMerge > Ratio) {
           // For debug, just print "L", so we'll see "L3=P3" for instance, which
diff --git a/llvm/test/tools/llvm-split/AMDGPU/large-kernels-merging.ll b/llvm/test/tools/llvm-split/AMDGPU/large-kernels-merging.ll
index 807fb2e5f33cea..2810e9853bebe3 100644
--- a/llvm/test/tools/llvm-split/AMDGPU/large-kernels-merging.ll
+++ b/llvm/test/tools/llvm-split/AMDGPU/large-kernels-merging.ll
@@ -15,19 +15,20 @@
 ; Also check w/o large kernels processing to verify they are indeed handled
 ; differently.
 
-; P0 is empty
-; CHECK0: declare
+; CHECK0: define internal void @HelperC()
+; CHECK0: define amdgpu_kernel void @C
 
-; CHECK1: define internal void @HelperC()
-; CHECK1: define amdgpu_kernel void @C
+; CHECK1: define internal void @large2()
+; CHECK1: define internal void @large1()
+; CHECK1: define internal void @large0()
+; CHECK1: define internal void @HelperB()
+; CHECK1: define amdgpu_kernel void @B
 
 ; CHECK2: define internal void @large2()
 ; CHECK2: define internal void @large1()
 ; CHECK2: define internal void @large0()
 ; CHECK2: define internal void @HelperA()
-; CHECK2: define internal void @HelperB()
 ; CHECK2: define amdgpu_kernel void @A
-; CHECK2: define amdgpu_kernel void @B
 
 ; NOLARGEKERNELS-CHECK0: define internal void @HelperC()
 ; NOLARGEKERNELS-CHECK0: define amdgpu_kernel void @C