Fix PR4419: handle defs of partial uses.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73816 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 36 insertions, 7 deletions

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 6228821691..bd845085bb 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -359,12 +359,11 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
     // That is, unless we are currently processing the last reference itself.
     LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
 
-  /* Partial uses. Mark register def dead and add implicit def of
-     sub-registers which are used.
-    FIXME: LiveIntervalAnalysis can't handle this yet!
-    EAX<dead>  = op  AL<imp-def>
-    That is, EAX def is dead but AL def extends pass it.
-    Enable this after live interval analysis is fixed to improve codegen!
+  // Partial uses. Mark register def dead and add implicit def of
+  // sub-registers which are used.
+  // EAX<dead>  = op  AL<imp-def>
+  // That is, EAX def is dead but AL def extends pass it.
+  // Enable this after live interval analysis is fixed to improve codegen!
   else if (!PhysRegUse[Reg]) {
     PhysRegDef[Reg]->addRegisterDead(Reg, TRI, true);
     for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
@@ -377,7 +376,7 @@ bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
           PartUses.erase(*SS);
       }
     }
-  } */
+  }
   else
     LastRefOrPartRef->addRegisterKilled(Reg, TRI, true);
   return true;
diff --git a/test/CodeGen/ARM/2009-06-19-RegScavengerAssert.ll b/test/CodeGen/ARM/2009-06-19-RegScavengerAssert.ll
new file mode 100644
index 0000000000..cbe2385ab2
--- /dev/null
+++ b/test/CodeGen/ARM/2009-06-19-RegScavengerAssert.ll
@@ -0,0 +1,30 @@
+; RUN: llvm-as < %s | llc -mtriple=armv6-eabi -mattr=+vfp2 -float-abi=hard
+; PR4419
+
+define float @__ieee754_acosf(float %x) nounwind {
+entry:
+	br i1 undef, label %bb, label %bb4
+
+bb:		; preds = %entry
+	ret float undef
+
+bb4:		; preds = %entry
+	br i1 undef, label %bb5, label %bb6
+
+bb5:		; preds = %bb4
+	ret float undef
+
+bb6:		; preds = %bb4
+	br i1 undef, label %bb11, label %bb12
+
+bb11:		; preds = %bb6
+	%0 = tail call float @__ieee754_sqrtf(float undef) nounwind		; <float> [#uses=1]
+	%1 = fmul float %0, -2.000000e+00		; <float> [#uses=1]
+	%2 = fadd float %1, 0x400921FB40000000		; <float> [#uses=1]
+	ret float %2
+
+bb12:		; preds = %bb6
+	ret float undef
+}
+
+declare float @__ieee754_sqrtf(float)