[llvm] [IR] Require index width to be ule pointer width (PR #70015)
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 24 01:36:02 PDT 2023
https://github.com/nikic created https://github.com/llvm/llvm-project/pull/70015
I don't think there is a use case for having an index type that is wider than the pointer type, and I'm not entirely clear what semantics this would even have.
Also clarify the GEP semantics to explicitly say that it only affects the bits up to the index type width.
>From 3a68c35692c64e98a523ecbc33a80fd14e3fdd64 Mon Sep 17 00:00:00 2001
From: Nikita Popov <npopov at redhat.com>
Date: Tue, 24 Oct 2023 10:27:26 +0200
Subject: [PATCH] [IR] Require index width to be ule pointer width
I don't think there is a use case for having an index type that is
wider than the pointer type, and I'm not entirely clear what
semantics this would even have.
Also clarify the GEP semantics to explicitly say that it only
affects the bits up to the index type width.
---
llvm/docs/LangRef.rst | 20 ++--
llvm/lib/IR/DataLayout.cpp | 2 +
.../ptrtoint-constantexpr-loop.ll | 97 -------------------
.../invalid-datalayout-index-size.ll | 3 +
.../test/Transforms/InferAlignment/ptrmask.ll | 15 +--
5 files changed, 18 insertions(+), 119 deletions(-)
create mode 100644 llvm/test/Assembler/invalid-datalayout-index-size.ll
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index e4625cae9fc53e1..3d26709a1eb17c4 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -2883,7 +2883,8 @@ as follows:
This specifies the *size* of a pointer and its ``<abi>`` and
``<pref>``\erred alignments for address space ``n``. ``<pref>`` is optional
and defaults to ``<abi>``. The fourth parameter ``<idx>`` is the size of the
- index that used for address calculation. If not
+ index that used for address calculation, which must be less than or equal
+ to the pointer size. If not
specified, the default index size is equal to the pointer size. All sizes
are in bits. The address space, ``n``, is optional, and if not specified,
denotes the default address space 0. The value of ``n`` must be
@@ -11061,13 +11062,16 @@ These rules are based on the assumption that no allocated object may cross
the unsigned address space boundary, and no allocated object may be larger
than half the pointer index type space.
-If the ``inbounds`` keyword is not present, the offsets are added to the
-base address with silently-wrapping two's complement arithmetic. If the
-offsets have a different width from the pointer's index type, they are
-sign-extended or truncated to the width of the pointer's index type. The result
-value of the ``getelementptr`` may be outside the object pointed to by the base
-pointer. The result value may not necessarily be used to access memory
-though, even if it happens to point into allocated storage. See the
+If the ``inbounds`` keyword is not present, the offsets are first
+sign-extended or truncated to the pointer's index type, and then added
+to the low bits of the base address up to the index type width, with
+silently-wrapping two's complement arithmetic. If the pointer size is larger
+than the index size, this means that the bits outside the index type width
+will not be affected.
+
+The result value of the ``getelementptr`` may be outside the object pointed
+to by the base pointer. The result value may not necessarily be used to access
+memory though, even if it happens to point into allocated storage. See the
:ref:`Pointer Aliasing Rules <pointeraliasing>` section for more
information.
diff --git a/llvm/lib/IR/DataLayout.cpp b/llvm/lib/IR/DataLayout.cpp
index d324c4b488f7294..c8ef232082554bf 100644
--- a/llvm/lib/IR/DataLayout.cpp
+++ b/llvm/lib/IR/DataLayout.cpp
@@ -649,6 +649,8 @@ Error DataLayout::setPointerAlignmentInBits(uint32_t AddrSpace, Align ABIAlign,
if (PrefAlign < ABIAlign)
return reportError(
"Preferred alignment cannot be less than the ABI alignment");
+ if (IndexBitWidth > TypeBitWidth)
+ return reportError("Index width cannot be larger than pointer width");
auto I = lower_bound(Pointers, AddrSpace,
[](const PointerAlignElem &A, uint32_t AddressSpace) {
diff --git a/llvm/test/Analysis/ScalarEvolution/ptrtoint-constantexpr-loop.ll b/llvm/test/Analysis/ScalarEvolution/ptrtoint-constantexpr-loop.ll
index ca39b0b40e31614..31a6a6ec0023e58 100644
--- a/llvm/test/Analysis/ScalarEvolution/ptrtoint-constantexpr-loop.ll
+++ b/llvm/test/Analysis/ScalarEvolution/ptrtoint-constantexpr-loop.ll
@@ -2,7 +2,6 @@
; RUN: opt < %s --data-layout="p:64:64:64:64" -S -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck --check-prefixes=PTR64_IDX64 %s
; RUN: opt < %s --data-layout="p:64:64:64:32" -S -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck --check-prefixes=PTR64_IDX32 %s
; RUN: opt < %s --data-layout="p:16:16:16:16" -S -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck --check-prefixes=PTR16_IDX16 %s
-; RUN: opt < %s --data-layout="p:16:16:16:32" -S -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck --check-prefixes=PTR16_IDX32 %s
@global = external hidden global [0 x i8]
@@ -63,24 +62,6 @@ define hidden ptr @trunc_ptr_to_i64(ptr %arg, ptr %arg10) {
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
;
-; PTR16_IDX32-LABEL: 'trunc_ptr_to_i64'
-; PTR16_IDX32-NEXT: Classifying expressions for: @trunc_ptr_to_i64
-; PTR16_IDX32-NEXT: %tmp = phi i32 [ 0, %bb ], [ %tmp18, %bb17 ]
-; PTR16_IDX32-NEXT: --> {0,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: %tmp12 = getelementptr i8, ptr %arg, i64 ptrtoint (ptr @global to i64)
-; PTR16_IDX32-NEXT: --> ((trunc i64 ptrtoint (ptr @global to i64) to i32) + %arg) U: [0,131071) S: [0,131071) Exits: ((trunc i64 ptrtoint (ptr @global to i64) to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp13 = bitcast ptr %tmp12 to ptr
-; PTR16_IDX32-NEXT: --> ((trunc i64 ptrtoint (ptr @global to i64) to i32) + %arg) U: [0,131071) S: [0,131071) Exits: ((trunc i64 ptrtoint (ptr @global to i64) to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp14 = load i32, ptr %tmp13, align 4
-; PTR16_IDX32-NEXT: --> %tmp14 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %bb11: Variant }
-; PTR16_IDX32-NEXT: %tmp18 = add i32 %tmp, 2
-; PTR16_IDX32-NEXT: --> {2,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @trunc_ptr_to_i64
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable constant max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
-;
bb:
br label %bb11
@@ -154,24 +135,6 @@ define hidden ptr @trunc_ptr_to_i32(ptr %arg, ptr %arg10) {
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
;
-; PTR16_IDX32-LABEL: 'trunc_ptr_to_i32'
-; PTR16_IDX32-NEXT: Classifying expressions for: @trunc_ptr_to_i32
-; PTR16_IDX32-NEXT: %tmp = phi i32 [ 0, %bb ], [ %tmp18, %bb17 ]
-; PTR16_IDX32-NEXT: --> {0,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: %tmp12 = getelementptr i8, ptr %arg, i32 ptrtoint (ptr @global to i32)
-; PTR16_IDX32-NEXT: --> (ptrtoint (ptr @global to i32) + %arg) U: [0,131071) S: [0,131071) Exits: (ptrtoint (ptr @global to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp13 = bitcast ptr %tmp12 to ptr
-; PTR16_IDX32-NEXT: --> (ptrtoint (ptr @global to i32) + %arg) U: [0,131071) S: [0,131071) Exits: (ptrtoint (ptr @global to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp14 = load i32, ptr %tmp13, align 4
-; PTR16_IDX32-NEXT: --> %tmp14 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %bb11: Variant }
-; PTR16_IDX32-NEXT: %tmp18 = add i32 %tmp, 2
-; PTR16_IDX32-NEXT: --> {2,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @trunc_ptr_to_i32
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable constant max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
-;
bb:
br label %bb11
@@ -245,24 +208,6 @@ define hidden ptr @trunc_ptr_to_i128(ptr %arg, ptr %arg10) {
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
; PTR16_IDX16-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
;
-; PTR16_IDX32-LABEL: 'trunc_ptr_to_i128'
-; PTR16_IDX32-NEXT: Classifying expressions for: @trunc_ptr_to_i128
-; PTR16_IDX32-NEXT: %tmp = phi i32 [ 0, %bb ], [ %tmp18, %bb17 ]
-; PTR16_IDX32-NEXT: --> {0,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: %tmp12 = getelementptr i8, ptr %arg, i128 ptrtoint (ptr @global to i128)
-; PTR16_IDX32-NEXT: --> ((trunc i128 ptrtoint (ptr @global to i128) to i32) + %arg) U: [0,131071) S: [0,131071) Exits: ((trunc i128 ptrtoint (ptr @global to i128) to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp13 = bitcast ptr %tmp12 to ptr
-; PTR16_IDX32-NEXT: --> ((trunc i128 ptrtoint (ptr @global to i128) to i32) + %arg) U: [0,131071) S: [0,131071) Exits: ((trunc i128 ptrtoint (ptr @global to i128) to i32) + %arg) LoopDispositions: { %bb11: Invariant }
-; PTR16_IDX32-NEXT: %tmp14 = load i32, ptr %tmp13, align 4
-; PTR16_IDX32-NEXT: --> %tmp14 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %bb11: Variant }
-; PTR16_IDX32-NEXT: %tmp18 = add i32 %tmp, 2
-; PTR16_IDX32-NEXT: --> {2,+,2}<%bb11> U: [0,-1) S: [-2147483648,2147483647) Exits: <<Unknown>> LoopDispositions: { %bb11: Computable }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @trunc_ptr_to_i128
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable constant max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable symbolic max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb11: Unpredictable predicated backedge-taken count.
-;
bb:
br label %bb11
@@ -319,18 +264,6 @@ define void @zext_ptr_to_i32(i32 %arg, i32 %arg6) {
; PTR16_IDX16-NEXT: Loop %bb7: Unpredictable symbolic max backedge-taken count.
; PTR16_IDX16-NEXT: Loop %bb7: Unpredictable predicated backedge-taken count.
;
-; PTR16_IDX32-LABEL: 'zext_ptr_to_i32'
-; PTR16_IDX32-NEXT: Classifying expressions for: @zext_ptr_to_i32
-; PTR16_IDX32-NEXT: %tmp = sub i32 %arg, ptrtoint (ptr @global to i32)
-; PTR16_IDX32-NEXT: --> ((-1 * ptrtoint (ptr @global to i32))<nsw> + %arg) U: full-set S: full-set Exits: ((-1 * ptrtoint (ptr @global to i32))<nsw> + %arg) LoopDispositions: { %bb7: Invariant }
-; PTR16_IDX32-NEXT: %tmp9 = select i1 %tmp8, i16 0, i16 1
-; PTR16_IDX32-NEXT: --> %tmp9 U: [0,2) S: [0,2) Exits: <<Unknown>> LoopDispositions: { %bb7: Variant }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @zext_ptr_to_i32
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable constant max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable symbolic max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable predicated backedge-taken count.
-;
bb:
br label %bb7
@@ -382,18 +315,6 @@ define void @sext_to_i32(i32 %arg, i32 %arg6) {
; PTR16_IDX16-NEXT: Loop %bb7: Unpredictable symbolic max backedge-taken count.
; PTR16_IDX16-NEXT: Loop %bb7: Unpredictable predicated backedge-taken count.
;
-; PTR16_IDX32-LABEL: 'sext_to_i32'
-; PTR16_IDX32-NEXT: Classifying expressions for: @sext_to_i32
-; PTR16_IDX32-NEXT: %tmp = sub i32 %arg, sext (i16 ptrtoint (ptr @global to i16) to i32)
-; PTR16_IDX32-NEXT: --> ((-1 * (sext i16 ptrtoint (ptr @global to i16) to i32))<nsw> + %arg) U: full-set S: full-set Exits: ((-1 * (sext i16 ptrtoint (ptr @global to i16) to i32))<nsw> + %arg) LoopDispositions: { %bb7: Invariant }
-; PTR16_IDX32-NEXT: %tmp9 = select i1 %tmp8, i16 0, i16 1
-; PTR16_IDX32-NEXT: --> %tmp9 U: [0,2) S: [0,2) Exits: <<Unknown>> LoopDispositions: { %bb7: Variant }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @sext_to_i32
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable constant max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable symbolic max backedge-taken count.
-; PTR16_IDX32-NEXT: Loop %bb7: Unpredictable predicated backedge-taken count.
-;
bb:
br label %bb7
@@ -463,24 +384,6 @@ define i64 @sext_like_noop(i32 %n) {
; PTR16_IDX16-NEXT: Predicates:
; PTR16_IDX16: Loop %for.body: Trip multiple is 1
;
-; PTR16_IDX32-LABEL: 'sext_like_noop'
-; PTR16_IDX32-NEXT: Classifying expressions for: @sext_like_noop
-; PTR16_IDX32-NEXT: %ii = sext i32 %i to i64
-; PTR16_IDX32-NEXT: --> (sext i32 {1,+,1}<nuw><%for.body> to i64) U: [-2147483648,2147483648) S: [-2147483648,2147483648) --> (-1 + (zext i32 ptrtoint (ptr @sext_like_noop to i32) to i64))<nsw> U: [-1,65535) S: [-1,65535)
-; PTR16_IDX32-NEXT: %div = sdiv i64 55555, %ii
-; PTR16_IDX32-NEXT: --> %div U: full-set S: full-set
-; PTR16_IDX32-NEXT: %i = phi i32 [ %inc, %for.body ], [ 1, %entry ]
-; PTR16_IDX32-NEXT: --> {1,+,1}<nuw><%for.body> U: [1,0) S: [1,0) Exits: (-1 + ptrtoint (ptr @sext_like_noop to i32))<nsw> LoopDispositions: { %for.body: Computable }
-; PTR16_IDX32-NEXT: %inc = add nuw i32 %i, 1
-; PTR16_IDX32-NEXT: --> {2,+,1}<nuw><%for.body> U: [2,0) S: [2,0) Exits: ptrtoint (ptr @sext_like_noop to i32) LoopDispositions: { %for.body: Computable }
-; PTR16_IDX32-NEXT: Determining loop execution counts for: @sext_like_noop
-; PTR16_IDX32-NEXT: Loop %for.body: backedge-taken count is (-2 + ptrtoint (ptr @sext_like_noop to i32))<nsw>
-; PTR16_IDX32-NEXT: Loop %for.body: constant max backedge-taken count is -1
-; PTR16_IDX32-NEXT: Loop %for.body: symbolic max backedge-taken count is (-2 + ptrtoint (ptr @sext_like_noop to i32))<nsw>
-; PTR16_IDX32-NEXT: Loop %for.body: Predicated backedge-taken count is (-2 + ptrtoint (ptr @sext_like_noop to i32))<nsw>
-; PTR16_IDX32-NEXT: Predicates:
-; PTR16_IDX32: Loop %for.body: Trip multiple is 1
-;
entry:
%cmp6 = icmp sgt i32 %n, 1
br label %for.body
diff --git a/llvm/test/Assembler/invalid-datalayout-index-size.ll b/llvm/test/Assembler/invalid-datalayout-index-size.ll
new file mode 100644
index 000000000000000..dc608cdd56a0405
--- /dev/null
+++ b/llvm/test/Assembler/invalid-datalayout-index-size.ll
@@ -0,0 +1,3 @@
+; RUN: not llvm-as < %s 2>&1 | FileCheck %s
+target datalayout = "p:64:64:64:128"
+; CHECK: Index width cannot be larger than pointer width
diff --git a/llvm/test/Transforms/InferAlignment/ptrmask.ll b/llvm/test/Transforms/InferAlignment/ptrmask.ll
index afab872d16d5eac..7fb0220e92b967e 100644
--- a/llvm/test/Transforms/InferAlignment/ptrmask.ll
+++ b/llvm/test/Transforms/InferAlignment/ptrmask.ll
@@ -1,7 +1,7 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
; RUN: opt < %s -passes=infer-alignment -S | FileCheck %s
-target datalayout = "p1:64:64:64:32-p2:64:64:64:128"
+target datalayout = "p1:64:64:64:32"
; ------------------------------------------------------------------------------
; load instructions
@@ -88,18 +88,5 @@ define i8 @smaller_index_type(ptr addrspace(1) %ptr) {
ret i8 %load
}
-define i8 @larger_index_type(ptr addrspace(2) %ptr) {
-; CHECK-LABEL: define i8 @larger_index_type
-; CHECK-SAME: (ptr addrspace(2) [[PTR:%.*]]) {
-; CHECK-NEXT: [[PTR2:%.*]] = call ptr addrspace(2) @llvm.ptrmask.p2.i128(ptr addrspace(2) [[PTR]], i128 -4)
-; CHECK-NEXT: [[LOAD:%.*]] = load i8, ptr addrspace(2) [[PTR2]], align 4
-; CHECK-NEXT: ret i8 [[LOAD]]
-;
- %ptr2 = call ptr addrspace(2) @llvm.ptrmask.p2.i128(ptr addrspace(2) %ptr, i128 -4)
- %load = load i8, ptr addrspace(2) %ptr2, align 1
- ret i8 %load
-}
-
declare ptr @llvm.ptrmask.p0.i64(ptr, i64)
declare ptr addrspace(1) @llvm.ptrmask.p1.i32(ptr addrspace(1), i32)
-declare ptr addrspace(2) @llvm.ptrmask.p2.i128(ptr addrspace(2), i128)
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