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llvm-mirror/test/Transforms/InstCombine/phi-known-bits-operand-order.ll
Florian Hahn 6ecdafe314 [ValueTracking] Fix recurrence detection to check both PHI operands.
Summary:
Currently we fail to compute known bits for recurrences where the
first incoming value is the start value of the recurrence.

Instead of exiting the loop when the first incoming value is not
the step of the recurrence, continue to check the second incoming
value.

The original code uses a loop to handle both cases, but incorrectly
exits instead of continuing.

Reviewers: lebedev.ri, spatel, nikic

Reviewed By: lebedev.ri

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66216

llvm-svn: 369088
2019-08-16 09:15:02 +00:00

100 lines
3.9 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
; Check that we can turn the icmp sle into icmp ult, regardless of the
; order of the incoming values of the PHI node.
declare i1 @cond()
define void @phi_recurrence_start_first() {
; CHECK-LABEL: @phi_recurrence_start_first(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WHILE_COND:%.*]]
; CHECK: while.cond:
; CHECK-NEXT: [[CELL_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[START:%.*]], [[FOR_COND26:%.*]] ]
; CHECK-NEXT: [[COND_V:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[COND_V]], label [[IF_THEN:%.*]], label [[WHILE_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[START]] = add nuw nsw i32 [[CELL_0]], 1
; CHECK-NEXT: br i1 [[COND_V]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
; CHECK: for.cond11:
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[START]], [[IF_THEN]] ], [ [[STEP:%.*]], [[FOR_COND11]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
; CHECK: for.cond26:
; CHECK-NEXT: br label [[WHILE_COND]]
; CHECK: while.end:
; CHECK-NEXT: ret void
;
entry:
br label %while.cond
while.cond: ; preds = %entry, %for.cond26
%cell.0 = phi i32 [ 0, %entry ], [ %start, %for.cond26 ]
%cond.v = call i1 @cond()
br i1 %cond.v, label %if.then, label %while.end
if.then: ; preds = %while.cond
%start = add nsw i32 %cell.0, 1
br i1 %cond.v, label %for.cond11, label %for.cond26
for.cond11: ; preds = %for.cond11, %if.then
%i.1 = phi i32 [ %start, %if.then ], [ %step, %for.cond11 ]
%cmp13 = icmp sle i32 %i.1, 99
%step = add nsw i32 %i.1, 1
br i1 %cmp13, label %for.cond11, label %while.end
for.cond26: ; preds = %if.then
br label %while.cond
while.end: ; preds = %while.cond, %for.cond11
ret void
}
define void @phi_recurrence_step_first() {
; CHECK-LABEL: @phi_recurrence_step_first(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WHILE_COND:%.*]]
; CHECK: while.cond:
; CHECK-NEXT: [[CELL_0:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[START:%.*]], [[FOR_COND26:%.*]] ]
; CHECK-NEXT: [[COND_V:%.*]] = call i1 @cond()
; CHECK-NEXT: br i1 [[COND_V]], label [[IF_THEN:%.*]], label [[WHILE_END:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[START]] = add nuw nsw i32 [[CELL_0]], 1
; CHECK-NEXT: br i1 [[COND_V]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
; CHECK: for.cond11:
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[STEP:%.*]], [[FOR_COND11]] ], [ [[START]], [[IF_THEN]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
; CHECK: for.cond26:
; CHECK-NEXT: br label [[WHILE_COND]]
; CHECK: while.end:
; CHECK-NEXT: ret void
;
entry:
br label %while.cond
while.cond: ; preds = %entry, %for.cond26
%cell.0 = phi i32 [ 0, %entry ], [ %start, %for.cond26 ]
%cond.v = call i1 @cond()
br i1 %cond.v, label %if.then, label %while.end
if.then: ; preds = %while.cond
%start = add nsw i32 %cell.0, 1
br i1 %cond.v, label %for.cond11, label %for.cond26
for.cond11: ; preds = %for.cond11, %if.then
%i.1 = phi i32 [ %step, %for.cond11 ], [ %start, %if.then]
%cmp13 = icmp sle i32 %i.1, 99
%step = add nsw i32 %i.1, 1
br i1 %cmp13, label %for.cond11, label %while.end
for.cond26: ; preds = %if.then
br label %while.cond
while.end: ; preds = %while.cond, %for.cond11
ret void
}