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llvm-mirror/test/Transforms/GVN/equality-assume.ll
Philip Reames 450197a8bc [GVN] Propagate simple equalities from assumes within the tail of the block 
This extends the existing logic for propagating constant expressions in an analogous manner for what we do across basic blocks. The core point is that we chose some order of operands, and canonicalize uses towards that one.

The heuristic used is inspired by the one used across blocks; in a follow up change, I'd plan to common them so that the cross block version uses the slightly stronger ordering herein. 

As noted by the TODOs in the code, there's a good amount of room for improving the existing code and making it more powerful.  Some follow up work planned.

Differential Revision: https://reviews.llvm.org/D66977

llvm-svn: 370791
2019-09-03 17:31:19 +00:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -gvn < %s | FileCheck %s
define i32 @test(i32* %p, i32 %v) {
; CHECK-LABEL: @test(
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret i32 [[V]]
;
%load = load i32, i32* %p
%c = icmp eq i32 %load, %v
call void @llvm.assume(i1 %c)
ret i32 %load
}
define i32 @reverse(i32* %p, i32 %v) {
; CHECK-LABEL: @reverse(
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret i32 [[V]]
;
%load = load i32, i32* %p
%c = icmp eq i32 %load, %v
call void @llvm.assume(i1 %c)
ret i32 %v
}
; Lack of equivalance due to +0.0 vs -0.0
define float @neg_float_oeq(float* %p, float %v) {
; CHECK-LABEL: @neg_float_oeq(
; CHECK-NEXT: [[LOAD:%.*]] = load float, float* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = fcmp oeq float [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret float [[LOAD]]
;
%load = load float, float* %p
%c = fcmp oeq float %load, %v
call void @llvm.assume(i1 %c)
ret float %load
}
; Lack of equivalance due to +0.0 vs -0.0
define float @neg_float_ueq(float* %p, float %v) {
; CHECK-LABEL: @neg_float_ueq(
; CHECK-NEXT: [[LOAD:%.*]] = load float, float* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = fcmp ueq float [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret float [[LOAD]]
;
%load = load float, float* %p
%c = fcmp ueq float %load, %v
call void @llvm.assume(i1 %c)
ret float %load
}
define float @float_oeq_constant(float* %p) {
; CHECK-LABEL: @float_oeq_constant(
; CHECK-NEXT: [[LOAD:%.*]] = load float, float* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = fcmp oeq float [[LOAD]], 5.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret float 5.000000e+00
;
%load = load float, float* %p
%c = fcmp oeq float %load, 5.0
call void @llvm.assume(i1 %c)
ret float %load
}
; Lack of equivalance due to Nan
define float @neq_float_ueq_constant(float* %p) {
; CHECK-LABEL: @neq_float_ueq_constant(
; CHECK-NEXT: [[LOAD:%.*]] = load float, float* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = fcmp ueq float [[LOAD]], 5.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret float [[LOAD]]
;
%load = load float, float* %p
%c = fcmp ueq float %load, 5.0
call void @llvm.assume(i1 %c)
ret float %load
}
define float @float_ueq_constant_nnas(float* %p) {
; CHECK-LABEL: @float_ueq_constant_nnas(
; CHECK-NEXT: [[LOAD:%.*]] = load float, float* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = fcmp nnan ueq float [[LOAD]], 5.000000e+00
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret float 5.000000e+00
;
%load = load float, float* %p
%c = fcmp nnan ueq float %load, 5.0
call void @llvm.assume(i1 %c)
ret float %load
}
define i32 @test2(i32* %p, i32 %v) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: ret i32 [[V]]
;
%load = load i32, i32* %p
%c = icmp eq i32 %load, %v
call void @llvm.assume(i1 %c)
%load2 = load i32, i32* %p
ret i32 %load2
}
define i32 @test3(i32* %p, i32 %v) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[P:%.*]]
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[LOAD]], [[V:%.*]]
; CHECK-NEXT: call void @llvm.assume(i1 [[C]])
; CHECK-NEXT: br i1 undef, label [[TAKEN:%.*]], label [[MERGE:%.*]]
; CHECK: taken:
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: ret i32 [[V]]
;
%load = load i32, i32* %p
%c = icmp eq i32 %load, %v
call void @llvm.assume(i1 %c)
br i1 undef, label %taken, label %merge
taken:
br label %merge
merge:
ret i32 %load
}
define i32 @trivial_constants(i32* %p) {
; CHECK-LABEL: @trivial_constants(
; CHECK-NEXT: br i1 undef, label [[TAKEN:%.*]], label [[MERGE:%.*]]
; CHECK: taken:
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: ret i32 0
;
%c = icmp eq i32 0, 0
call void @llvm.assume(i1 %c)
br i1 undef, label %taken, label %merge
taken:
br label %merge
merge:
ret i32 0
}
define i32 @conflicting_constants(i32* %p) {
; CHECK-LABEL: @conflicting_constants(
; CHECK-NEXT: store i8 undef, i8* null
; CHECK-NEXT: br i1 undef, label [[TAKEN:%.*]], label [[MERGE:%.*]]
; CHECK: taken:
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: ret i32 1
;
%c = icmp eq i32 0, 5
call void @llvm.assume(i1 %c)
br i1 undef, label %taken, label %merge
taken:
br label %merge
merge:
ret i32 1
}
declare void @llvm.assume(i1)
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