2a721374ae
Following some recent discussions, this changes the representation
of callbrs in IR. The current blockaddress arguments are replaced
with `!` label constraints that refer directly to callbr indirect
destinations:
; Before:
%res = callbr i8* asm "", "=r,r,i"(i8* %x, i8* blockaddress(@test8, %foo))
to label %asm.fallthrough [label %foo]
; After:
%res = callbr i8* asm "", "=r,r,!i"(i8* %x)
to label %asm.fallthrough [label %foo]
The benefit of this is that we can easily update the successors of
a callbr, without having to worry about also updating blockaddress
references. This should allow us to remove some limitations:
* Allow unrolling/peeling/rotation of callbr, or any other
clone-based optimizations
(https://github.com/llvm/llvm-project/issues/41834)
* Allow duplicate successors
(https://github.com/llvm/llvm-project/issues/45248)
This is just the IR representation change though, I will follow up
with patches to remove limtations in various transformation passes
that are no longer needed.
Differential Revision: https://reviews.llvm.org/D129288
115 lines
3.7 KiB
LLVM
115 lines
3.7 KiB
LLVM
; RUN: opt < %s -S -loop-reduce | FileCheck %s
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define void @testIVNext(i64* nocapture %a, i64 signext %m, i64 signext %n) {
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entry:
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br label %for.body
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for.body:
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%indvars.iv.prol = phi i64 [ %indvars.iv.next.prol, %for.body ], [ %m, %entry ]
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%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
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%uglygep138 = getelementptr i64, i64* %a, i64 %i
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store i64 55, i64* %uglygep138, align 4
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%indvars.iv.next.prol = add nuw nsw i64 %indvars.iv.prol, 1
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%i.next = add i64 %i, 1
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%i.cmp.not = icmp eq i64 %i.next, %n
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br i1 %i.cmp.not, label %for.exit, label %for.body
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; CHECK: entry:
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; CHECK: %0 = add i64 %n, %m
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; CHECK-NOT : %indvars.iv.next.prol
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; CHECK-NOT: %indvars.iv.prol
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; CHECK: %indvars.iv.unr = phi i64 [ %0, %for.exit ]
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for.exit:
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%indvars.iv.next.prol.lcssa = phi i64 [ %indvars.iv.next.prol, %for.body ]
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br label %exit
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exit:
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%indvars.iv.unr = phi i64 [ %indvars.iv.next.prol.lcssa, %for.exit ]
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ret void
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}
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define void @testIV(i64* nocapture %a, i64 signext %m, i64 signext %n) {
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entry:
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br label %for.body
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for.body:
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%iv.prol = phi i64 [ %iv.next.prol, %for.body ], [ %m, %entry ]
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%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
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%uglygep138 = getelementptr i64, i64* %a, i64 %i
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store i64 55, i64* %uglygep138, align 4
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%iv.next.prol = add nuw nsw i64 %iv.prol, 1
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%i.next = add i64 %i, 1
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%i.cmp.not = icmp eq i64 %i.next, %n
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br i1 %i.cmp.not, label %for.exit, label %for.body
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; CHECK: entry:
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; CHECK: %0 = add i64 %n, %m
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; CHECK: %1 = add i64 %0, -1
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; CHECK-NOT: %iv.next.prol
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; CHECK-NOT: %iv.prol
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; CHECK: %indvars.iv.unr = phi i64 [ %1, %for.exit ]
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for.exit:
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%iv.prol.lcssa = phi i64 [ %iv.prol, %for.body ]
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br label %exit
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exit:
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%indvars.iv.unr = phi i64 [%iv.prol.lcssa, %for.exit]
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ret void
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}
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define void @testNonIndVarPhi() {
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cont5820:
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br label %for.cond5821
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for.cond5821: ; preds = %cont5825, %cont5820
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%0 = phi i32 [ 0, %cont5825 ], [ 1, %cont5820 ]
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br label %cont5825
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cont5825: ; preds = %for.cond5821
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br i1 false, label %for.cond5821, label %for.cond6403
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for.cond6403: ; preds = %dead, %cont5825
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%1 = phi i32 [ %.lcssa221, %dead ], [ 0, %cont5825 ]
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br label %for.cond6418
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for.cond6418: ; preds = %cont6497, %for.cond6403
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%2 = phi i32 [ %0, %cont6497 ], [ %1, %for.cond6403 ]
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%3 = phi i64 [ 1, %cont6497 ], [ 0, %for.cond6403 ]
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%cmp6419 = icmp ule i64 %3, 0
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br i1 %cmp6419, label %cont6497, label %for.end6730
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cont6497: ; preds = %for.cond6418
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%conv6498 = sext i32 %2 to i64
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br label %for.cond6418
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for.end6730: ; preds = %for.cond6418
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; Check that we don't make changes for phis which are not considered
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; induction variables
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; CHECK: %.lcssa221 = phi i32 [ %2, %for.cond6418 ]
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%.lcssa221 = phi i32 [ %2, %for.cond6418 ]
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ret void
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dead: ; No predecessors!
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br label %for.cond6403
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}
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; Check that this doesn't crash
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define void @kernfs_path_from_node() {
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entry:
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callbr void asm sideeffect "", "!i"()
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to label %asm.fallthrough [label %while.body]
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asm.fallthrough: ; preds = %entry
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br label %while.body
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while.body: ; preds = %while.body, %asm.fallthrough, %entry
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%depth.04 = phi i32 [ %inc, %while.body ], [ 0, %asm.fallthrough ], [ 0, %entry ]
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%inc = add i32 %depth.04, 1
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br i1 false, label %while.end, label %while.body
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while.end: ; preds = %while.body
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%inc.lcssa = phi i32 [ %depth.04, %while.body ]
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store i32 %inc.lcssa, i32* null, align 4
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ret void
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}
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