[PATCH] D82635: [MSP430] Declare comparison LibCalls as returning i16 instead of i32

[Anatoly Trosinenko via Phabricator via llvm-commits]

atrosinenko created this revision.
atrosinenko added reviewers: awygle, pftbest.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

For TI's distribution of msp430-gcc

  msp430-elf-gcc -S -o- -Os -x c - <<< "int f(float a, float b) { return a != b; }"

does not mention R13 <https://reviews.llvm.org/source/pstl/> at all. `__libgcc_cmp_return__` machine mode is 2 byte on MSP430, as well.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D82635

Files:
  llvm/lib/Target/MSP430/MSP430ISelLowering.h
  llvm/test/CodeGen/MSP430/cmp-return-type.ll


Index: llvm/test/CodeGen/MSP430/cmp-return-type.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/MSP430/cmp-return-type.ll
@@ -0,0 +1,25 @@
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-m:e-p:16:16-i32:16-i64:16-f32:16-f64:16-a:8-n8:16-S16"
+target triple = "msp430"
+
+define i16 @f(float %a, float %b) optsize {
+  %cmp = fcmp une float %a, %b
+  %conv = zext i1 %cmp to i16
+; CHECK-LABEL: call #__mspabi_cmpf
+; CHECK-NOT:   r13
+; CHECK-LABEL: mov r2
+
+; This is quite fragile attempt to detect the return type:
+; Correct:
+;        call    #__mspabi_cmpf
+;        tst     r12
+;        mov     r2, r13
+; Incorrect:
+;        call    #__mspabi_cmpf
+;        bis     r12, r13        <-- checking (R12:R13)
+;        tst     r13
+;        mov     r2, r13
+
+  ret i16 %conv
+}
Index: llvm/lib/Target/MSP430/MSP430ISelLowering.h
===================================================================
--- llvm/lib/Target/MSP430/MSP430ISelLowering.h
+++ llvm/lib/Target/MSP430/MSP430ISelLowering.h
@@ -79,6 +79,10 @@
       return MVT::i8;
     }
 
+    MVT::SimpleValueType getCmpLibcallReturnType() const override {
+      return MVT::i16;
+    }
+
     /// LowerOperation - Provide custom lowering hooks for some operations.
     SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;
 


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