[DAGCombiner] Add test exposing bug in DAG combine.

[hgreving]

Summary

Adds a test in X86, exposing a bug in DAG combine eliminating stores that
are the same value but no the same address space.

[RKSimon]

LGTM

[spatel]

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

[hgreving]

Removed :gs versions in the test.
Added indexed store tests.

[hgreving]

In D102243#2750702, @spatel wrote:

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

Would you mind hinting me to the script? I barely work upstream, sorry for that.

[spatel]

In D102243#2750964, @hgreving wrote:

In D102243#2750702, @spatel wrote:

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

Would you mind hinting me to the script? I barely work upstream, sorry for that.

No problem - it's in the repo at:
utils/update_llc_test_checks.py ( https://github.com/llvm/llvm-project/blob/main/llvm/utils/update_llc_test_checks.py )

To run it, do something like this:
$ {path to}/update_llc_test_checks.py --llc={path to local}/llc dagcombine-dead-store.ll

Then, you can just run that same command after applying D102096 and rebuilding llc. No need to manually touch the test file unless it looks wrong/excessive.

[hgreving]

In D102243#2750964, @hgreving wrote:

In D102243#2750702, @spatel wrote:

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

Would you mind hinting me to the script? I barely work upstream, sorry for that.

Found, will update shortly.

[hgreving]

In D102243#2751006, @spatel wrote:

In D102243#2750964, @hgreving wrote:

In D102243#2750702, @spatel wrote:

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

Would you mind hinting me to the script? I barely work upstream, sorry for that.

No problem - it's in the repo at:
utils/update_llc_test_checks.py ( https://github.com/llvm/llvm-project/blob/main/llvm/utils/update_llc_test_checks.py )

To run it, do something like this:
$ {path to}/update_llc_test_checks.py --llc={path to local}/llc dagcombine-dead-store.ll

Then, you can just run that same command after applying D102096 and rebuilding llc. No need to manually touch the test file unless it looks wrong/excessive.

I had just found it a minute before this comment. Thanks. We can use this script downstream actually. Thanks for pointing it out.

[hgreving]

Used update_llc_test_checks.py for CHECKs.

[hgreving]

In D102243#2751071, @hgreving wrote:

In D102243#2751006, @spatel wrote:

In D102243#2750964, @hgreving wrote:

In D102243#2750702, @spatel wrote:

Is there some reason to not use scripted, auto-generated CHECK lines on this file?

Would you mind hinting me to the script? I barely work upstream, sorry for that.

No problem - it's in the repo at:
utils/update_llc_test_checks.py ( https://github.com/llvm/llvm-project/blob/main/llvm/utils/update_llc_test_checks.py )

To run it, do something like this:
$ {path to}/update_llc_test_checks.py --llc={path to local}/llc dagcombine-dead-store.ll

Then, you can just run that same command after applying D102096 and rebuilding llc. No need to manually touch the test file unless it looks wrong/excessive.

I had just found it a minute before this comment. Thanks. We can use this script downstream actually. Thanks for pointing it out.

Done.

[spatel]

LGTM

[hgreving]

Fix test's comment gibberish.

llvm/test/CodeGen/X86/dagcombine-dead-store.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-pc-linux | FileCheck %s
+
+; Checks that the stores aren't eliminated by the DAG combiner, because the address
+; spaces are different. In X86, we're checking this for the non-zero address space :fs.
+; The test's 'same' and 'diff' notation depicts whether the pointer value is the same
+; or different.
+
+; FIXME: DAG combine incorrectly eliminates store if pointer is of same value.
+
+define i32 @copy_fs_same() {
+; CHECK-LABEL: copy_fs_same:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl 1, %eax
+; CHECK-NEXT:    retl
+entry:
+   %0 = load i32, i32* inttoptr (i64 1 to i32*), align 4
+  store i32 %0, i32 addrspace(257)* inttoptr (i64 1 to i32 addrspace(257)*), align 4
+  ret i32 %0
+}
+
+define i32 @copy_fs_diff() {
+; CHECK-LABEL: copy_fs_diff:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl 1, %eax
+; CHECK-NEXT:    movl %eax, %fs:2
+; CHECK-NEXT:    retl
+entry:
+   %0 = load i32, i32* inttoptr (i64 1 to i32*), align 4
+  store i32 %0, i32 addrspace(257)* inttoptr (i64 2 to i32 addrspace(257)*), align 4
+  ret i32 %0
+}
+
+define void @output_fs_same(i32 %v) {
+; CHECK-LABEL: output_fs_same:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl %eax, 1
+; CHECK-NEXT:    retl
+entry:
+  store i32 %v, i32* inttoptr (i64 1 to i32*), align 4
+  store i32 %v, i32 addrspace(257)* inttoptr (i64 1 to i32 addrspace(257)*), align 4
+  ret void
+}
+
+define void @output_fs_diff(i32 %v) {
+; CHECK-LABEL: output_fs_diff:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl %eax, 1
+; CHECK-NEXT:    movl %eax, %fs:2
+; CHECK-NEXT:    retl
+entry:
+  store i32 %v, i32* inttoptr (i64 1 to i32*), align 4
+  store i32 %v, i32 addrspace(257)* inttoptr (i64 2 to i32 addrspace(257)*), align 4
+  ret void
+}
+
+define void @output_indexed_fs_same(i32 %v, i32* %b) {
+; CHECK-LABEL: output_indexed_fs_same:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT:    movl %eax, 168(%ecx)
+; CHECK-NEXT:    retl
+  %p = getelementptr i32, i32* %b, i64 42
+  %pa = addrspacecast i32* %p to i32 addrspace(257)*
+  store i32 %v, i32* %p, align 4
+  store i32 %v, i32 addrspace(257)* %pa, align 4
+  ret void
+}
+
+define void @output_indexed_fs_diff(i32 %v, i32* %b) {
+; CHECK-LABEL: output_indexed_fs_diff:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; CHECK-NEXT:    movl {{[0-9]+}}(%esp), %ecx
+; CHECK-NEXT:    movl %eax, 168(%ecx)
+; CHECK-NEXT:    movl %eax, %fs:184(%ecx)
+; CHECK-NEXT:    retl
+  %p = getelementptr i32, i32* %b, i64 42
+  %pa = addrspacecast i32* %p to i32 addrspace(257)*
+  %pad = getelementptr i32, i32 addrspace(257)* %pa, i64 4
+  store i32 %v, i32* %p, align 4
+  store i32 %v, i32 addrspace(257)* %pad, align 4
+  ret void
+}