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[SYCL] Turn off part of SimplifyCFG optimizations in SYCL mode. #5283

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Merged
bader merged 7 commits into from
Feb 2, 2022
Merged

[SYCL] Turn off part of SimplifyCFG optimizations in SYCL mode. #5283

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c9fa4aa
[SYCL] Turn off SimplifyCFG pass in SYCL mode.
maksimsab Jan 11, 2022
80b1377
simplify test. reduce the number of turned off passes. add turn off for
maksimsab Jan 26, 2022
e8dd5fd
apply clang-format
maksimsab Jan 27, 2022
c60f3f9
swtich clangxx to clang_cc1 in simplifycfg.cpp
maksimsab Jan 27, 2022
92bc3ee
Merge branch 'sycl' of https://github.com/intel/llvm into turn_off_si…
maksimsab Jan 31, 2022
43680ab
remove unnecessary modification
maksimsab Jan 31, 2022
632e7a2
remove unnecessary modifications
maksimsab Jan 31, 2022
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29 changes: 29 additions & 0 deletions clang/test/CodeGenSYCL/simplifycfg.cpp
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Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
// RUN: %clang_cc1 -fsycl-is-device -triple spir64-unknown-unknown -flegacy-pass-manager -mllvm -sycl-opt %s -emit-llvm -o - | FileCheck %s
// RUN: %clang_cc1 -fsycl-is-device -triple spir64-unknown-unknown -fno-legacy-pass-manager -mllvm -sycl-opt %s -emit-llvm -o - | FileCheck %s
//
// This test checks that foo (which is @_Z3foov) is called twice after O3 optimizations.
//
// Usually clang with SimplifyCFG pass optimizes constructs like:
// if (i % 2 == 0)
// func();
// else
// func();
//
// into one simple func() invocation.
// This behaviour might be wrong in cases when func's behaviour depends on
// a place where it is written.
// There is a relevant discussion about introducing
// a reliable tool for such cases: https://reviews.llvm.org/D85603

// CHECK: tail call spir_func void @_Z3foov()
// CHECK: tail call spir_func void @_Z3foov()

SYCL_EXTERNAL void foo();

SYCL_EXTERNAL void bar(int i) {
if (i % 2 == 0) {
foo();
} else {
foo();
}
}
8 changes: 6 additions & 2 deletions llvm/lib/Passes/PassBuilderPipelines.cpp
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Expand Up @@ -598,8 +598,12 @@ PassBuilder::buildFunctionSimplificationPipeline(OptimizationLevel Level,
for (auto &C : ScalarOptimizerLateEPCallbacks)
C(FPM, Level);

FPM.addPass(SimplifyCFGPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
if (SYCLOptimizationMode)
FPM.addPass(SimplifyCFGPass());
else
FPM.addPass(SimplifyCFGPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));

FPM.addPass(InstCombinePass());
invokePeepholeEPCallbacks(FPM, Level);

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8 changes: 6 additions & 2 deletions llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -541,8 +541,12 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
MPM.add(createLoopRerollPass());

// Merge & remove BBs and sink & hoist common instructions.
MPM.add(createCFGSimplificationPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
if (SYCLOptimizationMode)
MPM.add(createCFGSimplificationPass());
else
MPM.add(createCFGSimplificationPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));

// Clean up after everything.
MPM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, MPM);
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