[llvm] [AMDGPU][LowerModuleLDS] Refactor partially lowered module detection (PR #85793)
Pierre van Houtryve via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 19 07:10:52 PDT 2024
https://github.com/Pierre-vh created https://github.com/llvm/llvm-project/pull/85793
Refactor the logic that checks if a module contains mixed absolute/non-lowered LDS GVs.
The check now happens latter when the "worklists" are formed. This is because in some cases (OpenMP) we can have non-lowered GVs in a lowered module, and this is normal because those GVs are just unused and removed from the list at some point before the end of `getUsesOfLDSByFunction`.
Doing the check later ensures that if a mixed module is spotted, then it's a _real_ mixed module that needs rejection, not a module containing an intentionally ignored GV.
>From d578f7535ea6d7c87760d3ba7f187db714e8481c Mon Sep 17 00:00:00 2001
From: pvanhout <pierre.vanhoutryve at amd.com>
Date: Tue, 19 Mar 2024 15:10:07 +0100
Subject: [PATCH] [AMDGPU][LowerModuleLDS] Refactor partially lowered module
detection
Refactor the logic that checks if a module contains mixed absolute/non-lowered LDS GVs.
The check now happens latter when the "worklists" are formed. This is because in some cases (OpenMP) we can have non-lowered GVs in a lowered module, and this is normal because those GVs are just unused and removed from the list at some point before the end of `getUsesOfLDSByFunction`.
Doing the check later ensures that if a mixed module is spotted, then it's a _real_ mixed module that needs rejection, not a module containing an intentionally ignored GV.
---
.../AMDGPU/AMDGPULowerModuleLDSPass.cpp | 41 ++++++++++++-------
.../lds-reject-mixed-absolute-addresses.ll | 2 +-
2 files changed, 27 insertions(+), 16 deletions(-)
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
index b85cb26fdc9565..656f10e44c3bbc 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
@@ -340,26 +340,11 @@ class AMDGPULowerModuleLDS {
// Get uses from the current function, excluding uses by called functions
// Two output variables to avoid walking the globals list twice
- std::optional<bool> HasAbsoluteGVs;
for (auto &GV : M.globals()) {
if (!AMDGPU::isLDSVariableToLower(GV)) {
continue;
}
- // Check if the module is consistent: either all GVs are absolute (happens
- // when we run the pass more than once), or none are.
- const bool IsAbsolute = GV.isAbsoluteSymbolRef();
- if (HasAbsoluteGVs.has_value()) {
- if (*HasAbsoluteGVs != IsAbsolute) {
- report_fatal_error(
- "Module cannot mix absolute and non-absolute LDS GVs");
- }
- } else
- HasAbsoluteGVs = IsAbsolute;
-
- if (IsAbsolute)
- continue;
-
for (User *V : GV.users()) {
if (auto *I = dyn_cast<Instruction>(V)) {
Function *F = I->getFunction();
@@ -469,6 +454,31 @@ class AMDGPULowerModuleLDS {
}
}
+ // Verify that we fall into one of 2 cases:
+ // - All variables are absolute: this is a re-run of the pass
+ // so we don't have anything to do.
+ // - No variables are absolute.
+ std::optional<bool> HasAbsoluteGVs;
+ for (auto Map : {direct_map_kernel, indirect_map_kernel}) {
+ for (auto [Fn, GVs] : Map) {
+ for (auto GV : GVs) {
+ bool IsAbsolute = GV->isAbsoluteSymbolRef();
+ if (HasAbsoluteGVs.has_value()) {
+ if (*HasAbsoluteGVs != IsAbsolute) {
+ report_fatal_error(
+ "Module cannot mix absolute and non-absolute LDS GVs");
+ }
+ } else
+ HasAbsoluteGVs = IsAbsolute;
+ }
+ }
+ }
+
+ // If we only had absolute GVs, we have nothing to do, return an empty
+ // result.
+ if (HasAbsoluteGVs && *HasAbsoluteGVs)
+ return {FunctionVariableMap(), FunctionVariableMap()};
+
return {std::move(direct_map_kernel), std::move(indirect_map_kernel)};
}
@@ -1143,6 +1153,7 @@ class AMDGPULowerModuleLDS {
}
bool runOnModule(Module &M) {
+ dbgs() << "LowerModuleLDS: " << M.getName() << " (" << (void *)&M << ")\n";
CallGraph CG = CallGraph(M);
bool Changed = superAlignLDSGlobals(M);
diff --git a/llvm/test/CodeGen/AMDGPU/lds-reject-mixed-absolute-addresses.ll b/llvm/test/CodeGen/AMDGPU/lds-reject-mixed-absolute-addresses.ll
index b512a43aa10222..b1f4f2ef1ef535 100644
--- a/llvm/test/CodeGen/AMDGPU/lds-reject-mixed-absolute-addresses.ll
+++ b/llvm/test/CodeGen/AMDGPU/lds-reject-mixed-absolute-addresses.ll
@@ -8,7 +8,7 @@
define amdgpu_kernel void @kern() {
%val0 = load i32, ptr addrspace(3) @var1
%val1 = add i32 %val0, 4
- store i32 %val1, ptr addrspace(3) @var1
+ store i32 %val1, ptr addrspace(3) @var2
ret void
}
More information about the llvm-commits
mailing list