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[InstCombine] Add additional cost of phi tests (NFC) 

These check for undesirable folds for a cast of a loop phi.
This commit is contained in:
Nikita Popov 2022-06-10 15:48:34 +02:00
parent 959a9923de
commit 51bddfb1a0
1 changed files with 74 additions and 4 deletions
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78
llvm/test/Transforms/InstCombine/cast_phi.ll
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@ -253,13 +253,13 @@ define i64 @zext_from_legal_to_legal_type(i32 %x) {
; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
; CHECK: t:
; CHECK-NEXT: [[Y:%.*]] = call i32 @get_i32()
; CHECK-NEXT: [[PHITMP:%.*]] = zext i32 [[Y]] to i64
; CHECK-NEXT: [[PHI_CAST:%.*]] = zext i32 [[Y]] to i64
; CHECK-NEXT: br label [[EXIT:%.*]]
; CHECK: f:
; CHECK-NEXT: call void @bar()
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[PHITMP]], [[T]] ], [ 3, [[F]] ]
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[PHI_CAST]], [[T]] ], [ 3, [[F]] ]
; CHECK-NEXT: ret i64 [[P]]
;
entry:
@ -287,13 +287,13 @@ define i64 @zext_from_illegal_to_legal_type(i32 %x) {
; CHECK-NEXT: br i1 [[CMP]], label [[T:%.*]], label [[F:%.*]]
; CHECK: t:
; CHECK-NEXT: [[Y:%.*]] = call i3 @get_i3()
; CHECK-NEXT: [[PHITMP:%.*]] = zext i3 [[Y]] to i64
; CHECK-NEXT: [[PHI_CAST:%.*]] = zext i3 [[Y]] to i64
; CHECK-NEXT: br label [[EXIT:%.*]]
; CHECK: f:
; CHECK-NEXT: call void @bar()
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[PHITMP]], [[T]] ], [ 3, [[F]] ]
; CHECK-NEXT: [[P:%.*]] = phi i64 [ [[PHI_CAST]], [[T]] ], [ 3, [[F]] ]
; CHECK-NEXT: ret i64 [[P]]
;
entry:
@ -313,3 +313,73 @@ exit:
%r = zext i3 %p to i64
ret i64 %r
}
define i8 @trunc_in_loop_exit_block() {
; CHECK-LABEL: @trunc_in_loop_exit_block(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
; CHECK-NEXT: [[PHI:%.*]] = phi i8 [ 1, [[ENTRY]] ], [ [[PHI_CAST:%.*]], [[LOOP_LATCH]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[IV]], 100
; CHECK-NEXT: br i1 [[CMP]], label [[LOOP_LATCH]], label [[EXIT:%.*]]
; CHECK: loop.latch:
; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT: [[PHI_CAST]] = trunc i32 [[IV_NEXT]] to i8
; CHECK-NEXT: br label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: ret i8 [[PHI]]
;
entry:
br label %loop
loop:
%iv = phi i32 [ 0, %entry ], [ %iv.next, %loop.latch ]
%phi = phi i32 [ 1, %entry ], [ %iv.next, %loop.latch ]
%cmp = icmp ult i32 %iv, 100
br i1 %cmp, label %loop.latch, label %exit
loop.latch:
%iv.next = add i32 %iv, 1
br label %loop
exit:
%trunc = trunc i32 %phi to i8
ret i8 %trunc
}
define i32 @zext_in_loop_and_exit_block(i8 %step, i32 %end) {
; CHECK-LABEL: @zext_in_loop_and_exit_block(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[LOOP:%.*]]
; CHECK: loop:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[PHI_CAST:%.*]], [[LOOP_LATCH:%.*]] ]
; CHECK-NEXT: [[CMP_NOT:%.*]] = icmp eq i32 [[IV]], [[END:%.*]]
; CHECK-NEXT: br i1 [[CMP_NOT]], label [[EXIT:%.*]], label [[LOOP_LATCH]]
; CHECK: loop.latch:
; CHECK-NEXT: [[STEP_EXT:%.*]] = zext i8 [[STEP:%.*]] to i32
; CHECK-NEXT: [[IV_NEXT:%.*]] = add nuw nsw i32 [[IV]], [[STEP_EXT]]
; CHECK-NEXT: [[PHI_CAST]] = and i32 [[IV_NEXT]], 255
; CHECK-NEXT: br label [[LOOP]]
; CHECK: exit:
; CHECK-NEXT: ret i32 [[IV]]
;
entry:
br label %loop
loop:
%iv = phi i8 [ 0, %entry ], [ %iv.next.trunc, %loop.latch ]
%iv.ext = zext i8 %iv to i32
%cmp = icmp ne i32 %iv.ext, %end
br i1 %cmp, label %loop.latch, label %exit
loop.latch:
%step.ext = zext i8 %step to i32
%iv.next = add i32 %iv.ext, %step.ext
%iv.next.trunc = trunc i32 %iv.next to i8
br label %loop
exit:
%ext = zext i8 %iv to i32
ret i32 %ext
}