RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2024-12-13 14:47:00 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

[InstCombine] replace divide-by-constant checks with asserts; NFC

Browse Source 
These folds already have tests for scalar and vector types, except 
for the vector div-by-0 case, so I'm adding tests for that.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280115 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2016-08-30 17:31:34 +00:00
parent bb0403b31b
commit f097e134b1
2 changed files with 32 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -1971,15 +1971,6 @@ Instruction *InstCombiner::foldICmpUDivConstant(ICmpInst &Cmp,
Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp,
BinaryOperator *Div,
const APInt *C) {
// FIXME: These checks restrict all folds under here to scalar types.
ConstantInt *RHS = dyn_cast<ConstantInt>(Cmp.getOperand(1));
if (!RHS)
return nullptr;
ConstantInt *DivRHS = dyn_cast<ConstantInt>(Div->getOperand(1));
if (!DivRHS)
return nullptr;
// Fold: icmp pred ([us]div X, C2), C -> range test
// Fold this div into the comparison, producing a range check.
// Determine, based on the divide type, what the range is being
@ -2002,16 +1993,22 @@ Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp,
if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned())
return nullptr;
// FIXME: These 3 checks can be asserts.
if (*C2 == 0)
return nullptr; // The ProdOV computation fails on divide by zero.
if (DivIsSigned && C2->isAllOnesValue())
return nullptr; // The overflow computation also screws up here
if (*C2 == 1) {
// This eliminates some funny cases with INT_MIN.
Cmp.setOperand(0, Div->getOperand(0)); // X/1 == X.
return &Cmp;
}
// These constant divides should already be folded in InstSimplify.
assert(*C2 != 0 && "The ProdOV computation fails on divide by zero.");
assert(*C2 != 1 && "Funny cases with INT_MIN will fail.");
// This constant divide should already be folded in InstCombine.
assert(!(DivIsSigned && C2->isAllOnesValue()) &&
"The overflow computation will fail.");
// FIXME: These checks restrict all folds under here to scalar types.
ConstantInt *RHS = dyn_cast<ConstantInt>(Cmp.getOperand(1));
if (!RHS)
return nullptr;
ConstantInt *DivRHS = dyn_cast<ConstantInt>(Div->getOperand(1));
if (!DivRHS)
return nullptr;
// Compute Prod = CI * DivRHS. We are essentially solving an equation
// of form X/C2=C. We solve for X by multiplying C2 (DivRHS) and

17
test/Transforms/InstSimplify/undef.ll
View File

@ -1,4 +1,3 @@
; NOTE: Assertions have been autogenerated by update_test_checks.py
; RUN: opt -instsimplify -S < %s | FileCheck %s
define i64 @test0() {
@ -194,6 +193,14 @@ define i32 @test20(i32 %a) {
ret i32 %b
}
define <2 x i32> @test20vec(<2 x i32> %a) {
; CHECK-LABEL: @test20vec(
; CHECK-NEXT: ret <2 x i32> undef
;
%b = udiv <2 x i32> %a, zeroinitializer
ret <2 x i32> %b
}
define i32 @test21(i32 %a) {
; CHECK-LABEL: @test21(
; CHECK: ret i32 undef
@ -202,6 +209,14 @@ define i32 @test21(i32 %a) {
ret i32 %b
}
define <2 x i32> @test21vec(<2 x i32> %a) {
; CHECK-LABEL: @test21vec(
; CHECK-NEXT: ret <2 x i32> undef
;
%b = sdiv <2 x i32> %a, zeroinitializer
ret <2 x i32> %b
}
define i32 @test22(i32 %a) {
; CHECK-LABEL: @test22(
; CHECK: ret i32 undef