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AMDGPU: Force skip branches over calls
Unfortunately the way SIInsertSkips works is backwards, and is required for correctness. r338235 added handling of some special cases where skipping is mandatory to avoid side effects if no lanes are active. It conservatively handled asm correctly, but the same logic needs to apply to calls. Usually the call sequence code is larger than the skip threshold, although the way the count is computed is really broken, so I'm not sure if anything was likely to really hit this. llvm-svn: 361202
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; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=hawaii < %s | FileCheck -enable-var-scope -check-prefix=GCN %s | ||
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; A call should be skipped if all lanes are zero, since we don't know | ||
; what side effects should be avoided inside the call. | ||
define hidden void @func() #1 { | ||
ret void | ||
} | ||
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; GCN-LABEL: {{^}}if_call: | ||
; GCN: s_and_saveexec_b64 | ||
; GCN-NEXT: ; mask branch [[END:BB[0-9]+_[0-9]+]] | ||
; GCN-NEXT: s_cbranch_execz [[END]] | ||
; GCN: s_swappc_b64 | ||
; GCN: [[END]]: | ||
define void @if_call(i32 %flag) #0 { | ||
%cc = icmp eq i32 %flag, 0 | ||
br i1 %cc, label %call, label %end | ||
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call: | ||
call void @func() | ||
br label %end | ||
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end: | ||
ret void | ||
} | ||
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; GCN-LABEL: {{^}}if_asm: | ||
; GCN: s_and_saveexec_b64 | ||
; GCN-NEXT: ; mask branch [[END:BB[0-9]+_[0-9]+]] | ||
; GCN-NEXT: s_cbranch_execz [[END]] | ||
; GCN: ; sample asm | ||
; GCN: [[END]]: | ||
define void @if_asm(i32 %flag) #0 { | ||
%cc = icmp eq i32 %flag, 0 | ||
br i1 %cc, label %call, label %end | ||
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call: | ||
call void asm sideeffect "; sample asm", ""() | ||
br label %end | ||
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end: | ||
ret void | ||
} | ||
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; GCN-LABEL: {{^}}if_call_kernel: | ||
; GCN: s_and_saveexec_b64 | ||
; GCN-NEXT: ; mask branch [[END:BB[0-9]+_[0-9]+]] | ||
; GCN-NEXT: s_cbranch_execz [[END]] | ||
; GCN: s_swappc_b64 | ||
define amdgpu_kernel void @if_call_kernel() #0 { | ||
%id = call i32 @llvm.amdgcn.workitem.id.x() | ||
%cc = icmp eq i32 %id, 0 | ||
br i1 %cc, label %call, label %end | ||
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call: | ||
call void @func() | ||
br label %end | ||
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end: | ||
ret void | ||
} | ||
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declare i32 @llvm.amdgcn.workitem.id.x() #2 | ||
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attributes #0 = { nounwind } | ||
attributes #1 = { nounwind noinline } | ||
attributes #2 = { nounwind readnone speculatable } |