[llvm] 7d0145c - [AMDGPU] Use more consistemt way to avoid overflow in the scheduler

[Stanislav Mekhanoshin via llvm-commits]

Author: Stanislav Mekhanoshin
Date: 2023-01-23T10:59:46-08:00
New Revision: 7d0145cc47488b008316b040ec9629605c0ed0b8

URL: https://github.com/llvm/llvm-project/commit/7d0145cc47488b008316b040ec9629605c0ed0b8
DIFF: https://github.com/llvm/llvm-project/commit/7d0145cc47488b008316b040ec9629605c0ed0b8.diff

LOG: [AMDGPU] Use more consistemt way to avoid overflow in the scheduler

Use more consistent way to avoid overflow when calculating SGPR
and VGPR pressure limits.

Differential Revision: https://reviews.llvm.org/D142262

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
index 82923c13263f..afbd87ff97bb 100644
--- a/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNSchedStrategy.cpp
@@ -89,18 +89,10 @@ void GCNSchedStrategy::initialize(ScheduleDAGMI *DAG) {
   }
 
   // Subtract error margin and bias from register limits and avoid overflow.
-  SGPRCriticalLimit =
-      std::min(SGPRCriticalLimit - SGPRLimitBias, SGPRCriticalLimit);
-  SGPRCriticalLimit =
-      std::min(SGPRCriticalLimit - ErrorMargin, SGPRCriticalLimit);
-  VGPRCriticalLimit =
-      std::min(VGPRCriticalLimit - VGPRLimitBias, VGPRCriticalLimit);
-  VGPRCriticalLimit =
-      std::min(VGPRCriticalLimit - ErrorMargin, VGPRCriticalLimit);
-  SGPRExcessLimit = std::min(SGPRExcessLimit - SGPRLimitBias, SGPRExcessLimit);
-  SGPRExcessLimit = std::min(SGPRExcessLimit - ErrorMargin, SGPRExcessLimit);
-  VGPRExcessLimit = std::min(VGPRExcessLimit - VGPRLimitBias, VGPRExcessLimit);
-  VGPRExcessLimit = std::min(VGPRExcessLimit - ErrorMargin, VGPRExcessLimit);
+  SGPRCriticalLimit -= std::min(SGPRLimitBias + ErrorMargin, SGPRCriticalLimit);
+  VGPRCriticalLimit -= std::min(VGPRLimitBias + ErrorMargin, VGPRCriticalLimit);
+  SGPRExcessLimit -= std::min(SGPRLimitBias + ErrorMargin, SGPRExcessLimit);
+  VGPRExcessLimit -= std::min(VGPRLimitBias + ErrorMargin, VGPRExcessLimit);
 
   LLVM_DEBUG(dbgs() << "VGPRCriticalLimit = " << VGPRCriticalLimit
                     << ", VGPRExcessLimit = " << VGPRExcessLimit