[PATCH] D30829: [Thumb1] combine ADDC/SUBC with a negative immediate

[Phabricator via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rL297820: [Thumb1] Fix the bug when adding/subtracting -2147483648 (authored by askrobov).

Changed prior to commit:
  https://reviews.llvm.org/D30829?vs=91636&id=91852#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D30829

Files:
  llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
  llvm/trunk/test/CodeGen/Thumb/long.ll


Index: llvm/trunk/test/CodeGen/Thumb/long.ll
===================================================================
--- llvm/trunk/test/CodeGen/Thumb/long.ll
+++ llvm/trunk/test/CodeGen/Thumb/long.ll
@@ -194,3 +194,15 @@
 ; CHECK: movs r1, r3
 }
 
+; "sub 2147483648" has to be lowered into "add -2147483648"
+define i64 @f12(i64 %x, i64 %y) {
+entry:
+        %tmp1 = sub i64 %x, 2147483648
+        ret i64 %tmp1
+; CHECK-LABEL: f12:
+; CHECK: movs r2, #1
+; CHECK: lsls r2, r2, #31
+; CHECK: movs r3, #0
+; CHECK: adds r0, r0, r2
+; CHECK: sbcs r1, r3
+}
Index: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
@@ -9788,8 +9788,8 @@
   if (Subtarget->isThumb1Only()) {
     SDValue RHS = N->getOperand(1);
     if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS)) {
-      int64_t imm = C->getSExtValue();
-      if (imm < 0) {
+      int32_t imm = C->getSExtValue();
+      if (-imm > 0) {
         SDLoc DL(N);
         RHS = DAG.getConstant(-imm, DL, MVT::i32);
         unsigned Opcode = (N->getOpcode() == ARMISD::ADDC) ? ARMISD::SUBC
@@ -9806,8 +9806,8 @@
   if (Subtarget->isThumb1Only()) {
     SDValue RHS = N->getOperand(1);
     if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS)) {
-      int64_t imm = C->getSExtValue();
-      if (imm < 0) {
+      int32_t imm = C->getSExtValue();
+      if (-imm > 0) {
         SDLoc DL(N);
 
         // The with-carry-in form matches bitwise not instead of the negation.


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