[WebAssembly] Implement instruction selection for constant offsets in addresses.

Add instruction patterns for matching load and store instructions with constant
offsets in addresses. The code is fairly redundant due to the need to replicate
everything between imm, tglobaldadr, and texternalsym, but this appears to be
common tablegen practice. The main alternative appears to be to introduce
matching functions with C++ code, but sticking with purely generated matchers
seems better for now.

Also note that this doesn't yet support offsets from getelementptr, which will
be the most common case; that will depend on a change in target-independent code
in order to set the NoUnsignedWrap flag, which I'll submit separately. Until
then, the testcase uses ptrtoint+add+inttoptr with a nuw on the add.

Also implement isLegalAddressingMode with an approximation of this.

Differential Revision: http://reviews.llvm.org/D15538

llvm-svn: 255681

3 files changed, 189 insertions, 4 deletions

diff --git a/llvm/test/CodeGen/WebAssembly/global.ll b/llvm/test/CodeGen/WebAssembly/global.ll
index c6bc359a188..32a5e5c606c 100644
--- a/llvm/test/CodeGen/WebAssembly/global.ll
+++ b/llvm/test/CodeGen/WebAssembly/global.ll
@@ -10,8 +10,8 @@ target triple = "wasm32-unknown-unknown"
 @llvm.used = appending global [1 x i32*] [i32* @g], section "llvm.metadata"
 
 ; CHECK: foo:
-; CHECK: i32.const $push0=, answer{{$}}
-; CHECK-NEXT: i32.load $push1=, 0($pop0){{$}}
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK-NEXT: i32.load $push1=, answer($pop0){{$}}
 ; CHECK-NEXT: return $pop1{{$}}
 define i32 @foo() {
   %a = load i32, i32* @answer
diff --git a/llvm/test/CodeGen/WebAssembly/offset.ll b/llvm/test/CodeGen/WebAssembly/offset.ll
new file mode 100644
index 00000000000..75a0bc9ab6c
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/offset.ll
@@ -0,0 +1,185 @@
+; RUN: llc < %s -asm-verbose=false | FileCheck %s
+
+; Test constant load and store address offsets.
+
+target datalayout = "e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+; With an nuw add, we can fold an offset.
+
+; CHECK-LABEL: load_i32_with_folded_offset:
+; CHECK: i32.load  $push0=, 24($0){{$}}
+define i32 @load_i32_with_folded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  %t = load i32, i32* %s
+  ret i32 %t
+}
+
+; Without nuw, and even with nsw, we can't fold an offset.
+
+; CHECK-LABEL: load_i32_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i32.load  $push2=, 0($pop1){{$}}
+define i32 @load_i32_with_unfolded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  %t = load i32, i32* %s
+  ret i32 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_folded_offset:
+; CHECK: i64.load  $push0=, 24($0){{$}}
+define i64 @load_i64_with_folded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  %t = load i64, i64* %s
+  ret i64 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i64.load  $push2=, 0($pop1){{$}}
+define i64 @load_i64_with_unfolded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  %t = load i64, i64* %s
+  ret i64 %t
+}
+
+; Same as above but with store.
+
+; CHECK-LABEL: store_i32_with_folded_offset:
+; CHECK: i32.store $discard=, 24($0), $pop0{{$}}
+define void @store_i32_with_folded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  store i32 0, i32* %s
+  ret void
+}
+
+; Same as above but with store.
+
+; CHECK-LABEL: store_i32_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i32.store $discard=, 0($pop1), $pop2{{$}}
+define void @store_i32_with_unfolded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  store i32 0, i32* %s
+  ret void
+}
+
+; Same as above but with store with i64.
+
+; CHECK-LABEL: store_i64_with_folded_offset:
+; CHECK: i64.store $discard=, 24($0), $pop0{{$}}
+define void @store_i64_with_folded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  store i64 0, i64* %s
+  ret void
+}
+
+; Same as above but with store with i64.
+
+; CHECK-LABEL: store_i64_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i64.store $discard=, 0($pop1), $pop2{{$}}
+define void @store_i64_with_unfolded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  store i64 0, i64* %s
+  ret void
+}
+
+; When loading from a fixed address, materialize a zero.
+
+; CHECK-LABEL: load_i32_from_numeric_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.load  $push1=, 42($pop0){{$}}
+define i32 @load_i32_from_numeric_address() {
+  %s = inttoptr i32 42 to i32*
+  %t = load i32, i32* %s
+  ret i32 %t
+}
+
+; CHECK-LABEL: load_i32_from_global_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.load  $push1=, gv($pop0){{$}}
+@gv = global i32 0
+define i32 @load_i32_from_global_address() {
+  %t = load i32, i32* @gv
+  ret i32 %t
+}
+
+; CHECK-LABEL: store_i32_to_numeric_address:
+; CHECK: i32.const $0=, 0{{$}}
+; CHECK: i32.store $discard=, 42($0), $0{{$}}
+define void @store_i32_to_numeric_address() {
+  %s = inttoptr i32 42 to i32*
+  store i32 0, i32* %s
+  ret void
+}
+
+; CHECK-LABEL: store_i32_to_global_address:
+; CHECK: i32.const $0=, 0{{$}}
+; CHECK: i32.store $discard=, gv($0), $0{{$}}
+define void @store_i32_to_global_address() {
+  store i32 0, i32* @gv
+  ret void
+}
+
+; Fold an offset into a sign-extending load.
+
+; CHECK-LABEL: load_i8_s_with_folded_offset:
+; CHECK: i32.load8_s $push0=, 24($0){{$}}
+define i32 @load_i8_s_with_folded_offset(i8* %p) {
+  %q = ptrtoint i8* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i8*
+  %t = load i8, i8* %s
+  %u = sext i8 %t to i32
+  ret i32 %u
+}
+
+; Fold an offset into a zero-extending load.
+
+; CHECK-LABEL: load_i8_u_with_folded_offset:
+; CHECK: i32.load8_u $push0=, 24($0){{$}}
+define i32 @load_i8_u_with_folded_offset(i8* %p) {
+  %q = ptrtoint i8* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i8*
+  %t = load i8, i8* %s
+  %u = zext i8 %t to i32
+  ret i32 %u
+}
+
+; Fold an offset into a truncating store.
+
+; CHECK-LABEL: store_i8_with_folded_offset:
+; CHECK: i32.store8 $discard=, 24($0), $pop0{{$}}
+define void @store_i8_with_folded_offset(i8* %p) {
+  %q = ptrtoint i8* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i8*
+  store i8 0, i8* %s
+  ret void
+}
diff --git a/llvm/test/CodeGen/WebAssembly/store-results.ll b/llvm/test/CodeGen/WebAssembly/store-results.ll
index 84f24e6e549..73479e544db 100644
--- a/llvm/test/CodeGen/WebAssembly/store-results.ll
+++ b/llvm/test/CodeGen/WebAssembly/store-results.ll
@@ -26,7 +26,7 @@ entry:
 @pos = global %class.Vec3 zeroinitializer, align 4
 
 ; CHECK-LABEL: foo:
-; CHECK: i32.store $discard=, 0($pop0), $0{{$}}
+; CHECK: i32.store $discard=, pos($0), $0{{$}}
 define void @foo() {
 for.body.i:
   br label %for.body5.i
@@ -44,7 +44,7 @@ for.cond.cleanup4.i:
 }
 
 ; CHECK-LABEL: bar:
-; CHECK: i32.store $discard=, 0($0), $pop0{{$}}
+; CHECK: i32.store $discard=, pos($0), $0{{$}}
 define void @bar() {
 for.body.i:
   br label %for.body5.i