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llvm-project/llvm/test/Transforms/GVN/assume-equal.ll
Nikita Popov fb632ed237
[GVN] Handle provenance when propagating assume equality (#151953) 
If we have a known `p == p2` equality, we cannot replace `p2` with `p`
unless they are known to have the same provenance. GVN handles this when
propagating equalities from conditions, but not for assumes, as these go
through a different code path for uses in the same block.

Call canReplacePointersInUseIfEqual() before performing the replacement.
This is subject to the usual approximations (e.g. that we always allow
replacement with a dereferenceable constant and null).

This restriction does not appear to have any impact in practice.
2025-08-05 09:18:43 +02:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=gvn -S | FileCheck %s
%struct.A = type { ptr }
@_ZTV1A = available_externally unnamed_addr constant [4 x ptr] [ptr null, ptr @_ZTI1A, ptr @_ZN1A3fooEv, ptr @_ZN1A3barEv], align 8
@_ZTI1A = external constant ptr
; Checks if indirect calls can be replaced with direct
; assuming that %vtable == @_ZTV1A (with alignment).
; Checking const propagation across other BBs
define void @_Z1gb(i1 zeroext %p) {
; CHECK-LABEL: define void @_Z1gb(
; CHECK-SAME: i1 zeroext [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CALL:%.*]] = tail call noalias ptr @_Znwm(i64 8)
; CHECK-NEXT: tail call void @_ZN1AC1Ev(ptr [[CALL]])
; CHECK-NEXT: [[VTABLE:%.*]] = load ptr, ptr [[CALL]], align 8
; CHECK-NEXT: [[CMP_VTABLES:%.*]] = icmp eq ptr [[VTABLE]], getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP_VTABLES]])
; CHECK-NEXT: br i1 [[P]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
; CHECK: [[IF_THEN]]:
; CHECK-NEXT: [[CALL2:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: br label %[[IF_END:.*]]
; CHECK: [[IF_ELSE]]:
; CHECK-NEXT: [[CALL5:%.*]] = tail call i32 @_ZN1A3barEv(ptr [[CALL]])
; CHECK-NEXT: br label %[[IF_END]]
; CHECK: [[IF_END]]:
; CHECK-NEXT: ret void
;
entry:
%call = tail call noalias ptr @_Znwm(i64 8) #4
tail call void @_ZN1AC1Ev(ptr %call) #1
%vtable = load ptr, ptr %call, align 8
%cmp.vtables = icmp eq ptr %vtable, getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
tail call void @llvm.assume(i1 %cmp.vtables)
br i1 %p, label %if.then, label %if.else
if.then: ; preds = %entry
%0 = load ptr, ptr %vtable, align 8
%call2 = tail call i32 %0(ptr %call) #1
br label %if.end
if.else: ; preds = %entry
%vfn47 = getelementptr inbounds ptr, ptr %vtable, i64 1
%1 = load ptr, ptr %vfn47, align 8
%call5 = tail call i32 %1(ptr %call) #1
br label %if.end
if.end: ; preds = %if.else, %if.then
ret void
}
; Check integration with invariant.group handling
define void @invariantGroupHandling(i1 zeroext %p) {
; CHECK-LABEL: define void @invariantGroupHandling(
; CHECK-SAME: i1 zeroext [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CALL:%.*]] = tail call noalias ptr @_Znwm(i64 8)
; CHECK-NEXT: tail call void @_ZN1AC1Ev(ptr [[CALL]])
; CHECK-NEXT: [[VTABLE:%.*]] = load ptr, ptr [[CALL]], align 8, !invariant.group [[META0:![0-9]+]]
; CHECK-NEXT: [[CMP_VTABLES:%.*]] = icmp eq ptr [[VTABLE]], getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP_VTABLES]])
; CHECK-NEXT: br i1 [[P]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
; CHECK: [[IF_THEN]]:
; CHECK-NEXT: [[CALL2:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: [[CALLX:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: [[CALLY:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: [[UNKNOWN:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: br label %[[IF_END:.*]]
; CHECK: [[IF_ELSE]]:
; CHECK-NEXT: [[CALL5:%.*]] = tail call i32 @_ZN1A3barEv(ptr [[CALL]])
; CHECK-NEXT: br label %[[IF_END]]
; CHECK: [[IF_END]]:
; CHECK-NEXT: ret void
;
entry:
%call = tail call noalias ptr @_Znwm(i64 8) #4
tail call void @_ZN1AC1Ev(ptr %call) #1
%vtable = load ptr, ptr %call, align 8, !invariant.group !0
%cmp.vtables = icmp eq ptr %vtable, getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
tail call void @llvm.assume(i1 %cmp.vtables)
br i1 %p, label %if.then, label %if.else
if.then: ; preds = %entry
%0 = load ptr, ptr %vtable, align 8
%call2 = tail call i32 %0(ptr %call) #1
%vtable1 = load ptr, ptr %call, align 8, !invariant.group !0
%call1 = load ptr, ptr %vtable1, align 8
%callx = tail call i32 %call1(ptr %call) #1
%vtable2 = load ptr, ptr %call, align 8, !invariant.group !0
%call4 = load ptr, ptr %vtable2, align 8
%cally = tail call i32 %call4(ptr %call) #1
%vtable3 = load ptr, ptr %call, align 8, !invariant.group !0
%vfun = load ptr, ptr %vtable3, align 8
%unknown = tail call i32 %vfun(ptr %call) #1
br label %if.end
if.else: ; preds = %entry
%vfn47 = getelementptr inbounds ptr, ptr %vtable, i64 1
%1 = load ptr, ptr %vfn47, align 8
%call5 = tail call i32 %1(ptr %call) #1
br label %if.end
if.end: ; preds = %if.else, %if.then
ret void
}
; Checking const propagation in the same BB
define i32 @main() {
; CHECK-LABEL: define i32 @main() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CALL:%.*]] = tail call noalias ptr @_Znwm(i64 8)
; CHECK-NEXT: tail call void @_ZN1AC1Ev(ptr [[CALL]])
; CHECK-NEXT: [[VTABLE:%.*]] = load ptr, ptr [[CALL]], align 8
; CHECK-NEXT: [[CMP_VTABLES:%.*]] = icmp eq ptr [[VTABLE]], getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
; CHECK-NEXT: tail call void @llvm.assume(i1 [[CMP_VTABLES]])
; CHECK-NEXT: [[CALL2:%.*]] = tail call i32 @_ZN1A3fooEv(ptr [[CALL]])
; CHECK-NEXT: ret i32 0
;
entry:
%call = tail call noalias ptr @_Znwm(i64 8)
tail call void @_ZN1AC1Ev(ptr %call)
%vtable = load ptr, ptr %call, align 8
%cmp.vtables = icmp eq ptr %vtable, getelementptr inbounds ([4 x ptr], ptr @_ZTV1A, i64 0, i64 2)
tail call void @llvm.assume(i1 %cmp.vtables)
%0 = load ptr, ptr %vtable, align 8
%call2 = tail call i32 %0(ptr %call)
ret i32 0
}
; This tests checks const propatation with fcmp instruction.
define float @_Z1gf(float %p) {
; CHECK-LABEL: define float @_Z1gf(
; CHECK-SAME: float [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P_ADDR:%.*]] = alloca float, align 4
; CHECK-NEXT: [[F:%.*]] = alloca float, align 4
; CHECK-NEXT: store float [[P]], ptr [[P_ADDR]], align 4
; CHECK-NEXT: store float 3.000000e+00, ptr [[F]], align 4
; CHECK-NEXT: [[CMP:%.*]] = fcmp oeq float 3.000000e+00, [[P]]
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret float 3.000000e+00
;
entry:
%p.addr = alloca float, align 4
%f = alloca float, align 4
store float %p, ptr %p.addr, align 4
store float 3.000000e+00, ptr %f, align 4
%0 = load float, ptr %p.addr, align 4
%1 = load float, ptr %f, align 4
%cmp = fcmp oeq float %1, %0 ; note const on lhs
call void @llvm.assume(i1 %cmp)
ret float %0
}
define float @_Z1hf(float %p) {
; CHECK-LABEL: define float @_Z1hf(
; CHECK-SAME: float [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P_ADDR:%.*]] = alloca float, align 4
; CHECK-NEXT: store float [[P]], ptr [[P_ADDR]], align 4
; CHECK-NEXT: [[CMP:%.*]] = fcmp nnan ueq float [[P]], 3.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret float 3.000000e+00
;
entry:
%p.addr = alloca float, align 4
store float %p, ptr %p.addr, align 4
%0 = load float, ptr %p.addr, align 4
%cmp = fcmp nnan ueq float %0, 3.000000e+00
call void @llvm.assume(i1 %cmp)
ret float %0
}
define float @_Z1if(float %p) {
; CHECK-LABEL: define float @_Z1if(
; CHECK-SAME: float [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[P_ADDR:%.*]] = alloca float, align 4
; CHECK-NEXT: store float [[P]], ptr [[P_ADDR]], align 4
; CHECK-NEXT: [[CMP:%.*]] = fcmp ueq float [[P]], 3.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret float [[P]]
;
entry:
%p.addr = alloca float, align 4
store float %p, ptr %p.addr, align 4
%0 = load float, ptr %p.addr, align 4
%cmp = fcmp ueq float %0, 3.000000e+00 ; no nnan flag - can't propagate
call void @llvm.assume(i1 %cmp)
ret float %0
}
; This test checks if constant propagation works for multiple node edges
define i32 @_Z1ii(i32 %p) {
; CHECK-LABEL: define i32 @_Z1ii(
; CHECK-SAME: i32 [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P]], 42
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label %[[BB2:.*]], label %[[BB2]]
; CHECK: [[BB2]]:
; CHECK-NEXT: br i1 true, label %[[BB2]], label %[[BB2]]
; CHECK: [[BB0:.*:]]
; CHECK-NEXT: ret i32 42
;
entry:
%cmp = icmp eq i32 %p, 42
call void @llvm.assume(i1 %cmp)
br i1 %cmp, label %bb2, label %bb2
bb2:
call void @llvm.assume(i1 true)
br i1 %cmp, label %bb2, label %bb2
ret i32 %p
}
define i32 @_Z1ij(i32 %p) {
; CHECK-LABEL: define i32 @_Z1ij(
; CHECK-SAME: i32 [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P]], 42
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label %[[BB2:.*]], label %[[BB2]]
; CHECK: [[BB2]]:
; CHECK-NEXT: br i1 true, label %[[BB2]], label %[[BB2]]
; CHECK: [[BB0:.*:]]
; CHECK-NEXT: ret i32 42
;
entry:
%cmp = icmp eq i32 %p, 42
call void @llvm.assume(i1 %cmp)
br i1 %cmp, label %bb2, label %bb2
bb2:
%cmp2 = icmp eq i32 %p, 42
call void @llvm.assume(i1 %cmp2)
br i1 %cmp, label %bb2, label %bb2
ret i32 %p
}
define i32 @_Z1ik(i32 %p) {
; CHECK-LABEL: define i32 @_Z1ik(
; CHECK-SAME: i32 [[P:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[P]], 42
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: br i1 true, label %[[BB2:.*]], label %[[BB3:.*]]
; CHECK: [[BB2]]:
; CHECK-NEXT: store i8 poison, ptr null, align 1
; CHECK-NEXT: ret i32 15
; CHECK: [[BB3]]:
; CHECK-NEXT: ret i32 17
;
entry:
%cmp = icmp eq i32 %p, 42
call void @llvm.assume(i1 %cmp)
br i1 %cmp, label %bb2, label %bb3
bb2:
%cmp3 = icmp eq i32 %p, 43
call void @llvm.assume(i1 %cmp3)
ret i32 15
bb3:
ret i32 17
}
; This test checks if GVN can do the constant propagation correctly
; when there are multiple uses of the same assume value in the
; basic block that has a loop back-edge pointing to itself.
;
define i32 @_Z1il(i32 %val, i1 %k) {
; CHECK-LABEL: define i32 @_Z1il(
; CHECK-SAME: i32 [[VAL:%.*]], i1 [[K:%.*]]) {
; CHECK-NEXT: br label %[[NEXT:.*]]
; CHECK: [[NEXT]]:
; CHECK-NEXT: tail call void @llvm.assume(i1 [[K]])
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[VAL]], 50
; CHECK-NEXT: br i1 [[CMP]], label %[[NEXT]], label %[[MEH:.*]]
; CHECK: [[MEH]]:
; CHECK-NEXT: ret i32 0
;
br label %next
next:
tail call void @llvm.assume(i1 %k)
tail call void @llvm.assume(i1 %k)
%cmp = icmp eq i32 %val, 50
br i1 %cmp, label %next, label %meh
meh:
ret i32 0
}
; This test checks if GVN can prevent the constant propagation correctly
; in the successor blocks that are not dominated by the basic block
; with the assume instruction.
;
define i1 @_z1im(i32 %val, i1 %k, i1 %j) {
; CHECK-LABEL: define i1 @_z1im(
; CHECK-SAME: i32 [[VAL:%.*]], i1 [[K:%.*]], i1 [[J:%.*]]) {
; CHECK-NEXT: br i1 [[J]], label %[[NEXT:.*]], label %[[MEH:.*]]
; CHECK: [[NEXT]]:
; CHECK-NEXT: tail call void @llvm.assume(i1 [[K]])
; CHECK-NEXT: br label %[[MEH]]
; CHECK: [[MEH]]:
; CHECK-NEXT: ret i1 [[K]]
;
br i1 %j, label %next, label %meh
next:
tail call void @llvm.assume(i1 %k)
tail call void @llvm.assume(i1 %k)
br label %meh
meh:
ret i1 %k
}
define i8 @assume_ptr_eq_different_prov_matters(ptr %p, ptr %p2) {
; CHECK-LABEL: define i8 @assume_ptr_eq_different_prov_matters(
; CHECK-SAME: ptr [[P:%.*]], ptr [[P2:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[P]], [[P2]]
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[V:%.*]] = load i8, ptr [[P2]], align 1
; CHECK-NEXT: ret i8 [[V]]
;
%cmp = icmp eq ptr %p, %p2
call void @llvm.assume(i1 %cmp)
%v = load i8, ptr %p2
ret i8 %v
}
define i1 @assume_ptr_eq_different_prov_does_not_matter(ptr %p, ptr %p2) {
; CHECK-LABEL: define i1 @assume_ptr_eq_different_prov_does_not_matter(
; CHECK-SAME: ptr [[P:%.*]], ptr [[P2:%.*]]) {
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[P]], [[P2]]
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[C:%.*]] = icmp eq ptr [[P]], null
; CHECK-NEXT: ret i1 [[C]]
;
%cmp = icmp eq ptr %p, %p2
call void @llvm.assume(i1 %cmp)
%c = icmp eq ptr %p2, null
ret i1 %c
}
define i8 @assume_ptr_eq_same_prov(ptr %p, i64 %x) {
; CHECK-LABEL: define i8 @assume_ptr_eq_same_prov(
; CHECK-SAME: ptr [[P:%.*]], i64 [[X:%.*]]) {
; CHECK-NEXT: [[P2:%.*]] = getelementptr i8, ptr [[P]], i64 [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[P]], [[P2]]
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: [[V:%.*]] = load i8, ptr [[P]], align 1
; CHECK-NEXT: ret i8 [[V]]
;
%p2 = getelementptr i8, ptr %p, i64 %x
%cmp = icmp eq ptr %p, %p2
call void @llvm.assume(i1 %cmp)
%v = load i8, ptr %p2
ret i8 %v
}
declare noalias ptr @_Znwm(i64)
declare void @_ZN1AC1Ev(ptr)
declare void @llvm.assume(i1)
declare i32 @_ZN1A3fooEv(ptr)
declare i32 @_ZN1A3barEv(ptr)
!0 = !{!"struct A"}
;.
; CHECK: [[META0]] = !{!"struct A"}
;.
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