[PATCH] D110372: [AMDGPU] Limit promote alloca max size in functions

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGcf74ef134c9a: [AMDGPU] Limit promote alloca max size in functions (authored by rampitec).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110372/new/

https://reviews.llvm.org/D110372

Files:
  llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
  llvm/test/CodeGen/AMDGPU/vector-alloca-limits.ll


Index: llvm/test/CodeGen/AMDGPU/vector-alloca-limits.ll
===================================================================
--- llvm/test/CodeGen/AMDGPU/vector-alloca-limits.ll
+++ llvm/test/CodeGen/AMDGPU/vector-alloca-limits.ll
@@ -131,6 +131,38 @@
   ret void
 }
 
+; OPT-LABEL: @alloca_9xi64_max256(
+; OPT-NOT: alloca
+; OPT: <9 x i64>
+; LIMIT32: alloca
+; LIMIT32-NOT: <9 x i64>
+define amdgpu_kernel void @alloca_9xi64_max256(i64 addrspace(1)* %out, i32 %index) #2 {
+entry:
+  %tmp = alloca [9 x i64], addrspace(5)
+  %x = getelementptr [9 x i64], [9 x i64] addrspace(5)* %tmp, i32 0, i32 0
+  store i64 0, i64 addrspace(5)* %x
+  %tmp1 = getelementptr [9 x i64], [9 x i64] addrspace(5)* %tmp, i32 0, i32 %index
+  %tmp2 = load i64, i64 addrspace(5)* %tmp1
+  store i64 %tmp2, i64 addrspace(1)* %out
+  ret void
+}
+
+; OPT-LABEL: @func_alloca_9xi64_max256(
+; OPT: alloca
+; OPT-NOT: <9 x i64>
+; LIMIT32: alloca
+; LIMIT32-NOT: <9 x i64>
+define void @func_alloca_9xi64_max256(i64 addrspace(1)* %out, i32 %index) #2 {
+entry:
+  %tmp = alloca [9 x i64], addrspace(5)
+  %x = getelementptr [9 x i64], [9 x i64] addrspace(5)* %tmp, i32 0, i32 0
+  store i64 0, i64 addrspace(5)* %x
+  %tmp1 = getelementptr [9 x i64], [9 x i64] addrspace(5)* %tmp, i32 0, i32 %index
+  %tmp2 = load i64, i64 addrspace(5)* %tmp1
+  store i64 %tmp2, i64 addrspace(1)* %out
+  ret void
+}
+
 attributes #0 = { "amdgpu-flat-work-group-size"="1,1024" }
 attributes #1 = { "amdgpu-flat-work-group-size"="1,512" }
 attributes #2 = { "amdgpu-flat-work-group-size"="1,256" }
Index: llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
@@ -21,6 +21,7 @@
 #include "llvm/IR/IntrinsicsR600.h"
 #include "llvm/Pass.h"
 #include "llvm/Target/TargetMachine.h"
+#include "Utils/AMDGPUBaseInfo.h"
 
 #define DEBUG_TYPE "amdgpu-promote-alloca"
 
@@ -176,6 +177,10 @@
   if (IsAMDGCN) {
     const GCNSubtarget &ST = TM.getSubtarget<GCNSubtarget>(F);
     MaxVGPRs = ST.getMaxNumVGPRs(ST.getWavesPerEU(F).first);
+    // A non-entry function has only 32 caller preserved registers.
+    // Do not promote alloca which will force spilling.
+    if (!AMDGPU::isEntryFunctionCC(F.getCallingConv()))
+      MaxVGPRs = std::min(MaxVGPRs, 32u);
   } else {
     MaxVGPRs = 128;
   }
@@ -1107,6 +1112,10 @@
   if (TM.getTargetTriple().getArch() == Triple::amdgcn) {
     const GCNSubtarget &ST = TM.getSubtarget<GCNSubtarget>(F);
     MaxVGPRs = ST.getMaxNumVGPRs(ST.getWavesPerEU(F).first);
+    // A non-entry function has only 32 caller preserved registers.
+    // Do not promote alloca which will force spilling.
+    if (!AMDGPU::isEntryFunctionCC(F.getCallingConv()))
+      MaxVGPRs = std::min(MaxVGPRs, 32u);
   } else {
     MaxVGPRs = 128;
   }


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