[WebAssembly] Fix uses of FrameIndex as store values

Previously the code assumed all uses of FI on loads and stores were as
addresses. This checks whether the use is the address or a value and
handles the latter case as it does for non-memory instructions.

llvm-svn: 259306

3 files changed, 17 insertions, 6 deletions

diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
index df541f8c499..af970929bfa 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
@@ -125,6 +125,8 @@ inline unsigned GetDefaultP2Align(unsigned Opcode) {
   }
 }
 
+/// The operand number of the load or store address in load/store instructions.
+static const unsigned MemOpAddressOperandNo = 2;
 /// The operand number of the stored value in a store instruction.
 static const unsigned StoreValueOperandNo = 4;
 
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
index 3397f598759..607fd6e79c2 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegisterInfo.cpp
@@ -63,9 +63,9 @@ void WebAssemblyRegisterInfo::eliminateFrameIndex(
   const MachineFrameInfo &MFI = *MF.getFrameInfo();
   int64_t FrameOffset = MFI.getStackSize() + MFI.getObjectOffset(FrameIndex);
 
-  if (MI.mayLoadOrStore()) {
-    // If this is a load or store, make it relative to SP and fold the frame
-    // offset directly in.
+  if (MI.mayLoadOrStore() && FIOperandNum == WebAssembly::MemOpAddressOperandNo) {
+    // If this is the address operand of a load or store, make it relative to SP
+    // and fold the frame offset directly in.
     assert(FrameOffset >= 0 && MI.getOperand(1).getImm() >= 0);
     int64_t Offset = MI.getOperand(1).getImm() + FrameOffset;
 
diff --git a/llvm/test/CodeGen/WebAssembly/userstack.ll b/llvm/test/CodeGen/WebAssembly/userstack.ll
index 4da1324260a..435e1dd0b84 100644
--- a/llvm/test/CodeGen/WebAssembly/userstack.ll
+++ b/llvm/test/CodeGen/WebAssembly/userstack.ll
@@ -78,9 +78,10 @@ define void @allocarray() {
 
 declare void @ext_func(i64* %ptr)
 ; CHECK-LABEL: non_mem_use
-define void @non_mem_use() {
- ; CHECK: i32.const [[L2:.+]]=, 16
+define void @non_mem_use(i8** %addr) {
+ ; CHECK: i32.const [[L2:.+]]=, 48
  ; CHECK-NEXT: i32.sub [[SP:.+]]=, {{.+}}, [[L2]]
+ %buf = alloca [27 x i8], align 16
  %r = alloca i64
  %r2 = alloca i64
  ; %r is at SP+8
@@ -91,6 +92,13 @@ define void @non_mem_use() {
  ; %r2 is at SP+0, no add needed
  ; CHECK-NEXT: call ext_func@FUNCTION, [[SP]]
  call void @ext_func(i64* %r2)
+ ; Use as a value, but in a store
+ ; %buf is at SP+16
+ ; CHECK: i32.const [[OFF:.+]]=, 16
+ ; CHECK-NEXT: i32.add [[VAL:.+]]=, [[SP]], [[OFF]]
+ ; CHECK-NEXT: i32.store {{.*}}=, 0($0), [[VAL]]
+ %gep = getelementptr inbounds [27 x i8], [27 x i8]* %buf, i32 0, i32 0
+ store i8* %gep, i8** %addr
  ret void
 }
 
@@ -151,4 +159,5 @@ define void @dynamic_static_alloca(i32 %alloc) {
  ; CHECK-NEXT: i32.store [[SP]]=, 0([[L4]]), [[SP]]
  ret void
 }
-; TODO: test aligned alloc
+
+; TODO: test over-aligned alloca