e203a67f4c
Currently, `__constant__` variables do not get unconditionally marked as `constant` in IR, which seems a bit odd given their definition. This is generally inconsequential for NVPTX/AMDGPU, since said variables get emitted in the constant address space for those BEs. However, it is potentially significant for e.g. HIP-on-SPIR-V cases, as SPIR-V does not allow casts to/from the constant AS (`UniformConstant`), which forces `__constant__` variables to be emitted in the global AS, thus making IR constness meaningful.
51 lines
1.5 KiB
LLVM
51 lines
1.5 KiB
LLVM
; RUN: opt < %s -S -passes=globalopt | FileCheck %s
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; RUN: opt < %s -passes=early-cse | opt -S -passes=globalopt | FileCheck %s --check-prefix=CHECK-CONSTANT
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; This global is externally_initialized, which may modify the value between
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; it's static initializer and any code in this module being run, so the only
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; write to it cannot be merged into the static initialiser.
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; CHECK: @a = internal unnamed_addr externally_initialized global i32 undef
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@a = internal externally_initialized global i32 undef
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; This global is stored to by the external initialization, so cannot be
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; constant-propagated and removed, despite the fact that there are no writes
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; to it.
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; CHECK: @b = internal unnamed_addr externally_initialized global i32 undef
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@b = internal externally_initialized global i32 undef
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; This constant global is externally_initialized, which may modify the value
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; between its static const initializer and any code in this module being run, so
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; the read from it cannot be const propagated
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@c = internal externally_initialized constant i32 42
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define void @foo() {
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; CHECK-LABEL: foo
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entry:
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; CHECK: store i32 42, ptr @a
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store i32 42, ptr @a
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ret void
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}
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define i32 @bar() {
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; CHECK-LABEL: bar
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entry:
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; CHECK: %val = load i32, ptr @a
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%val = load i32, ptr @a
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ret i32 %val
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}
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define i32 @baz() {
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; CHECK-LABEL: baz
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entry:
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; CHECK: %val = load i32, ptr @b
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%val = load i32, ptr @b
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ret i32 %val
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}
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define i32 @bam() {
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; CHECK-CONSTANT-LABEL: bam
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entry:
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; CHECK-CONSTANT: %val = load i32, ptr @c
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%val = load i32, ptr @c
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ret i32 %val
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}
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