[BranchFolding] Set correct mem refs

[flyingforyou]

Summary

We might merge MBBICommon and MBBI's MMOs.

[reames]

Wow, yeah. Oops on my part.

LGTM

p.s. Can you *please* add a test case that covers this? It would have caught my typo to start with.

[flyingforyou]

Update test case.

lib/CodeGen/BranchFolding.cpp

while (CommonTailLen--) {
     while ((MBBICommon != MBBIECommon) && MBBICommon->isDebugValue())
       ++MBBICommon;
 
     assert(MBBICommon != MBBIECommon &&
            "Reached BB end within common tail length!");
     assert(MBBICommon->isIdenticalTo(&*MBBI) && "Expected matching MIIs!");
 
     if (MBBICommon->mayLoad() || MBBICommon->mayStore())
-      MBBICommon->setMemRefs(MBBI->mergeMemRefsWith(*MBBI));
+      MBBICommon->setMemRefs(MBBICommon->mergeMemRefsWith(*MBBI));
 
     ++MBBI;
     ++MBBICommon;
   }
 }
 
 // See if any of the blocks in MergePotentials (which all have a common single
 // successor, or all have no successor) can be tail-merged.  If there is a

test/CodeGen/AArch64/branch-folder-merge-mmos.ll

+; RUN: opt < %s -O3 | llc -march=aarch64 -mtriple=aarch64-none-linux-gnu -stop-after branch-folder -o /dev/null | FileCheck %s
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+
+; Function Attrs: nounwind
+define void @test(float* %test_arr) #0 {
+entry:
+  %test_arr.addr = alloca float*, align 8
+  store float* %test_arr, float** %test_arr.addr, align 8
+  %0 = load float*, float** %test_arr.addr, align 8
+  %arrayidx = getelementptr inbounds float, float* %0, i64 0
+  %1 = load float, float* %arrayidx, align 4
+  %2 = load float*, float** %test_arr.addr, align 8
+  %arrayidx1 = getelementptr inbounds float, float* %2, i64 1
+  %3 = load float, float* %arrayidx1, align 4
+  %sub = fsub float %1, %3
+  %4 = load float*, float** %test_arr.addr, align 8
+  %arrayidx2 = getelementptr inbounds float, float* %4, i64 0
+  store float %sub, float* %arrayidx2, align 4
+  ret void
+}
+
+; Function Attrs: nounwind
+define void @foo(i32 %a, i32 %b, float* %foo_arr) #0 {
+; CHECK: (load 4 from %ir.arrayidx1.i2), (load 4 from %ir.arrayidx1.i)
+entry:
+  %a.addr = alloca i32, align 4
+  %b.addr = alloca i32, align 4
+  %foo_arr.addr = alloca float*, align 8
+  store i32 %a, i32* %a.addr, align 4
+  store i32 %b, i32* %b.addr, align 4
+  store float* %foo_arr, float** %foo_arr.addr, align 8
+  %0 = load i32, i32* %a.addr, align 4
+  %cmp = icmp sgt i32 %0, 0
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:                                          ; preds = %entry
+  %1 = load float*, float** %foo_arr.addr, align 8
+  call void @test(float* %1)
+  br label %if.end3
+
+if.end:                                           ; preds = %entry
+  %2 = load i32, i32* %b.addr, align 4
+  %cmp1 = icmp sgt i32 %2, 0
+  br i1 %cmp1, label %if.then2, label %if.end3
+
+if.then2:                                         ; preds = %if.end
+  %3 = load float*, float** %foo_arr.addr, align 8
+  call void @test(float* %3)
+  br label %if.end3
+
+if.end3:                                          ; preds = %if.then, %if.then2, %if.end
+  ret void
+}