From 533e57a729c2a982fa425688362f35586a4be1df Mon Sep 17 00:00:00 2001
From: Andrew Nolan <anolan@lanl.gov>
Date: Thu, 1 Oct 2026 10:07:46 -0700
Subject: [PATCH 1/2] Disable floating point contractions on GPU archs

Also disabling fuse, multiply, add optimazation explicity where needed.
---
 components/omega/src/CMakeLists.txt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/components/omega/src/CMakeLists.txt b/components/omega/src/CMakeLists.txt
index a2f1ae537f58..ae1a07e462bf 100644
--- a/components/omega/src/CMakeLists.txt
+++ b/components/omega/src/CMakeLists.txt
@@ -27,6 +27,22 @@ target_compile_definitions(
     OMEGA_VECTOR_LENGTH=${OMEGA_VECTOR_LENGTH}
 )
 
+# Disable floating point contraction (e.g. fused multiply-add) for GPU
+# architectures. Needed for ERS and PEM test to pass COMPARE step
+if (OMEGA_ARCH STREQUAL "CUDA")
+  target_compile_options(OmegaLibFlags INTERFACE
+    $<$<COMPILE_LANGUAGE:CXX>:--fmad=false -Xcompiler -ffp-contract=off>
+  )
+elseif (OMEGA_ARCH STREQUAL "HIP")
+   target_compile_options(OmegaLibFlags INTERFACE
+      $<$<COMPILE_LANGUAGE:CXX>:-ffp-contract=off>
+   )
+elseif (OMEGA_ARCH STREQUAL "SYCL")
+   target_compile_options(OmegaLibFlags INTERFACE
+      $<$<COMPILE_LANGUAGE:CXX>:-fp-model=precise -ffp-contract=off>
+   )
+endif()
+
 if(OMEGA_SINGLE_PRECISION)
   target_compile_definitions(
       OmegaLibFlags

From 63fc21ec1880f55b5b150944e0b348e8be9b8d21 Mon Sep 17 00:00:00 2001
From: Youngsung Kim <youngsung.kim.act2@gmail.com>
Date: Fri, 23 Oct 2026 09:46:36 -0400
Subject: [PATCH 2/2] Add OMEGA_DISABLE_FP_CONTRACT CMake option

Put the flags that disable floating point contraction on CUDA, HIP and SYCL behind a CMake option, OMEGA_DISABLE_FP_CONTRACT, which defaults to ON. Building with -DOMEGA_DISABLE_FP_CONTRACT=OFF leaves contraction to the compiler, as before, for comparing performance.
---
 components/omega/OmegaBuild.cmake   |  1 +
 components/omega/src/CMakeLists.txt | 25 ++++++++++++++-----------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/components/omega/OmegaBuild.cmake b/components/omega/OmegaBuild.cmake
index bcbec9e954d4..2d4eb54fe10d 100644
--- a/components/omega/OmegaBuild.cmake
+++ b/components/omega/OmegaBuild.cmake
@@ -28,6 +28,7 @@ macro(common)
   option(OMEGA_LOG_FLUSH "Turn on unbuffered logging (default OFF)." OFF)
   option(OMEGA_TEST_CDASH "Turn on CDash support (default ON)." ON)
   option(OMEGA_EXTERNAL_PROF "Integration of Omega timers with external profiling tools (default OFF)." OFF)
+  option(OMEGA_DISABLE_FP_CONTRACT "Disable floating point contraction on GPU architectures (default ON)." ON)
 
   if("${OMEGA_BUILD_TYPE}" STREQUAL "Debug" OR "${OMEGA_BUILD_TYPE}" STREQUAL "DEBUG")
     set(OMEGA_DEBUG ON)
diff --git a/components/omega/src/CMakeLists.txt b/components/omega/src/CMakeLists.txt
index ae1a07e462bf..288318ae2066 100644
--- a/components/omega/src/CMakeLists.txt
+++ b/components/omega/src/CMakeLists.txt
@@ -28,19 +28,22 @@ target_compile_definitions(
 )
 
 # Disable floating point contraction (e.g. fused multiply-add) for GPU
-# architectures. Needed for ERS and PEM test to pass COMPARE step
-if (OMEGA_ARCH STREQUAL "CUDA")
-  target_compile_options(OmegaLibFlags INTERFACE
-    $<$<COMPILE_LANGUAGE:CXX>:--fmad=false -Xcompiler -ffp-contract=off>
-  )
-elseif (OMEGA_ARCH STREQUAL "HIP")
-   target_compile_options(OmegaLibFlags INTERFACE
+# architectures. Needed for ERS and PEM test to pass COMPARE step.
+# Controlled by OMEGA_DISABLE_FP_CONTRACT (default ON)
+if (OMEGA_DISABLE_FP_CONTRACT)
+  if (OMEGA_ARCH STREQUAL "CUDA")
+    target_compile_options(OmegaLibFlags INTERFACE
+      $<$<COMPILE_LANGUAGE:CXX>:--fmad=false -Xcompiler -ffp-contract=off>
+    )
+  elseif (OMEGA_ARCH STREQUAL "HIP")
+    target_compile_options(OmegaLibFlags INTERFACE
       $<$<COMPILE_LANGUAGE:CXX>:-ffp-contract=off>
-   )
-elseif (OMEGA_ARCH STREQUAL "SYCL")
-   target_compile_options(OmegaLibFlags INTERFACE
+    )
+  elseif (OMEGA_ARCH STREQUAL "SYCL")
+    target_compile_options(OmegaLibFlags INTERFACE
       $<$<COMPILE_LANGUAGE:CXX>:-fp-model=precise -ffp-contract=off>
-   )
+    )
+  endif()
 endif()
 
 if(OMEGA_SINGLE_PRECISION)