Use ldr for movs out of stack slots (instead of mov reg, [sp/fp]).

src/IceInstARM32.cpp

@@ -313,8 +313,18 @@ template <> void InstARM32Mov::emit(const Cfg *Func) const {
   assert(getSrcSize() == 1);
   Variable *Dest = getDest();
   if (Dest->hasReg()) {
-    Str << "\t"
-        << "mov" << getPredicate() << "\t";
+    const char *Opcode = "mov";
+    Operand *Src0 = getSrc(0);
+    if (const auto *Src0V = llvm::dyn_cast<Variable>(Src0)) {
+      if (!Src0V->hasReg()) {
+        Opcode = "ldr"; // Always load the full stack slot (vs ldrb, ldrh).
+      }
+    } else {
+      // If Src isn't a variable, it shouldn't be a memory operand either
+      // (otherwise Opcode will have to be ldr).
+      assert(!llvm::isa<OperandARM32Mem>(Src0));
+    }
+    Str << "\t" << Opcode << getPredicate() << "\t";
     getDest()->emit(Func);
     Str << ", ";
     getSrc(0)->emit(Func);

tests_lit/llvm2ice_tests/alloc.ll

@@ -15,6 +15,10 @@
 ; RUN:   --disassemble --target arm32 -i %s --args -O2 --skip-unimplemented \
 ; RUN:   | %if --need=target_ARM32 --command FileCheck --check-prefix ARM32 %s
 
+; RUN: %if --need=target_ARM32 --command %p2i --filetype=asm --assemble \
+; RUN:   --disassemble --target arm32 -i %s --args -Om1 --skip-unimplemented \
+; RUN:   | %if --need=target_ARM32 --command FileCheck --check-prefix ARM32 %s
+
 define void @fixed_416_align_16(i32 %n) {
 entry:
   %array = alloca i8, i32 416, align 16

tests_lit/llvm2ice_tests/branch-opt.ll

@@ -12,11 +12,15 @@
 ; TODO(jvoung): Stop skipping unimplemented parts (via --skip-unimplemented)
 ; once enough infrastructure is in. Also, switch to --filetype=obj
 ; when possible.
-; Also test Om1 when addProlog is done.
 ; RUN: %if --need=target_ARM32 --command %p2i --filetype=asm --assemble \
 ; RUN:   --disassemble --target arm32 -i %s --args -O2 --skip-unimplemented \
 ; RUN:   | %if --need=target_ARM32 --command FileCheck --check-prefix ARM32O2 %s
 
+; RUN: %if --need=target_ARM32 --command %p2i --filetype=asm --assemble \
+; RUN:   --disassemble --target arm32 -i %s --args -Om1 --skip-unimplemented \
+; RUN:   | %if --need=target_ARM32 --command FileCheck \
+; RUN:   --check-prefix ARM32OM1 %s
+
 declare void @dummy()
 
 ; An unconditional branch to the next block should be removed.
@@ -44,6 +48,11 @@ next:
 ; ARM32O2: bl {{.*}} dummy
 ; ARM32O2-NEXT: bl {{.*}} dummy
 
+; ARM32OM1-LABEL: testUncondToNextBlock
+; ARM32OM1: bl {{.*}} dummy
+; ARM32OM1-NEXT: b
+; ARM32OM1-NEXT: bl {{.*}} dummy
+
 ; For a conditional branch with a fallthrough to the next block, the
 ; fallthrough branch should be removed.
 define void @testCondFallthroughToNextBlock(i32 %arg) {
@@ -88,6 +97,17 @@ target:
 ; ARM32O2-NEXT: bl
 ; ARM32O2-NEXT: bx lr
 
+; ARM32OM1-LABEL: testCondFallthroughToNextBlock
+; ARM32OM1: cmp {{.*}}, #123
+; ARM32OM1-NEXT: movge {{.*}}, #1
+; ARM32OM1: cmp {{.*}}, #0
+; ARM32OM1: bne
+; ARM32OM1: b
+; ARM32OM1: bl
+; ARM32OM1: bx lr
+; ARM32OM1: bl
+; ARM32OM1: bx lr
+
 ; For a conditional branch with the next block as the target and a
 ; different block as the fallthrough, the branch condition should be
 ; inverted, the fallthrough block changed to the target, and the
@@ -134,3 +154,14 @@ target:
 ; ARM32O2-NEXT: bx lr
 ; ARM32O2-NEXT: bl
 ; ARM32O2-NEXT: bx lr
+
+; ARM32OM1-LABEL: testCondTargetNextBlock
+; ARM32OM1: cmp {{.*}}, #123
+; ARM32OM1: movge {{.*}}, #1
+; ARM32OM1: cmp {{.*}}, #0
+; ARM32OM1: bne
+; ARM32OM1: b
+; ARM32OM1: bl
+; ARM32OM1: bx lr
+; ARM32OM1: bl
+; ARM32OM1: bx lr