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99ca015392
Teach LLVM optimize to more precisely in the presence of "deopt" operand bundles. "deopt" operand bundles imply that the call they're attached to is at least `readonly` (i.e. they don't imply clobber semantics), and they don't capture their bundle operands. llvm-svn: 254118
52 lines
1.7 KiB
LLVM
52 lines
1.7 KiB
LLVM
; RUN: opt -S -basicaa -gvn < %s | FileCheck %s
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declare void @argmemonly_function(i32 *) argmemonly
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define i32 @test0(i32* %P, i32* noalias %P2) {
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; CHECK-LABEL: @test0(
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%v1 = load i32, i32* %P
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; CHECK: %v1 = load i32, i32* %P
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call void @argmemonly_function(i32* %P2) [ "tag"() ]
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; CHECK: call void @argmemonly_function(
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%v2 = load i32, i32* %P
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; CHECK: %v2 = load i32, i32* %P
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%diff = sub i32 %v1, %v2
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; CHECK: %diff = sub i32 %v1, %v2
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ret i32 %diff
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; CHECK: ret i32 %diff
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}
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define i32 @test1(i32* %P, i32* noalias %P2) {
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; CHECK-LABEL: @test1(
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%v1 = load i32, i32* %P
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call void @argmemonly_function(i32* %P2) argmemonly [ "tag"() ]
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; CHECK: call void @argmemonly_function(
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%v2 = load i32, i32* %P
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%diff = sub i32 %v1, %v2
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ret i32 %diff
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; CHECK: ret i32 0
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}
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define i32 @test2(i32* %P, i32* noalias %P2) {
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; Note: in this test we //can// GVN %v1 and %v2 into one value in theory. Calls
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; with deopt operand bundles are not argmemonly because they *read* the entire
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; heap, but they don't write to any location in the heap if the callee does not
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; deoptimize the caller. This fact, combined with the fact that
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; @argmemonly_function is, well, an argmemonly function, can be used to conclude
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; that %P is not written to at the callsite. However LLVM currently cannot
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; describe the "does not write to non-args, and reads the entire heap" effect on
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; a callsite.
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; CHECK-LABEL: @test2(
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%v1 = load i32, i32* %P
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; CHECK: %v1 = load i32, i32* %P
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call void @argmemonly_function(i32* %P2) [ "deopt"() ]
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; CHECK: call void @argmemonly_function(
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%v2 = load i32, i32* %P
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; CHECK: %v2 = load i32, i32* %P
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%diff = sub i32 %v1, %v2
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; CHECK: %diff = sub i32 %v1, %v2
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ret i32 %diff
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; CHECK: ret i32 %diff
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}
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