[LoopDist] Update the pragma info of loop distribute, NFC (#69825)

Base on D19403, the exact pragma of distribute is
  `#pragma clang loop distribute`

Author: vfdff

flang/test/Driver/optimization-remark.f90

@@ -47,7 +47,7 @@
 ! MISSED-REGEX-LOOP-ONLY:       optimization-remark.f90:76:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
 
 
-! ANALYSIS-REGEX-LOOP-ONLY:     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! ANALYSIS-REGEX-LOOP-ONLY:     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ! ANALYSIS-REGEX-LOOP-ONLY:     Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
 ! ANALYSIS-REGEX-LOOP-ONLY-NOT: remark: {{.*}}: IR instruction count changed from {{[0-9]+}} to {{[0-9]+}}; Delta: {{-?[0-9]+}} [-Rpass-analysis=size-info]
 
@@ -56,10 +56,10 @@
 
 ! MISSED:                       optimization-remark.f90:77:7: remark: failed to hoist load with loop-invariant address because load is conditionally executed [-Rpass-missed=licm]
 ! MISSED:                       optimization-remark.f90:76:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
-! MISSED-NOT:                   optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! MISSED-NOT:                   optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ! MISSED-NOT:                   Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
 
-! ANALYSIS:                     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! ANALYSIS:                     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ! ANALYSIS:                     Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
 ! ANALYSIS:                     remark: {{.*}}: IR instruction count changed from {{[0-9]+}} to {{[0-9]+}}; Delta: {{-?[0-9]+}} [-Rpass-analysis=size-info]
 ! ANALYSIS-NOT:                 optimization-remark.f90:77:7: remark: failed to hoist load with loop-invariant address because load is conditionally executed [-Rpass-missed=licm]

llvm/lib/Analysis/LoopAccessAnalysis.cpp

@@ -2532,7 +2532,7 @@ void LoopAccessInfo::emitUnsafeDependenceRemark() {
       HasForcedDistribution
           ? "unsafe dependent memory operations in loop."
           : "unsafe dependent memory operations in loop. Use "
-            "#pragma loop distribute(enable) to allow loop distribution "
+            "#pragma clang loop distribute(enable) to allow loop distribution "
             "to attempt to isolate the offending operations into a separate "
             "loop";
   OptimizationRemarkAnalysis &R =

llvm/lib/Transforms/Scalar/LoopDistribute.cpp

@@ -104,9 +104,9 @@ static cl::opt<unsigned> DistributeSCEVCheckThreshold(
 static cl::opt<unsigned> PragmaDistributeSCEVCheckThreshold(
     "loop-distribute-scev-check-threshold-with-pragma", cl::init(128),
     cl::Hidden,
-    cl::desc(
-        "The maximum number of SCEV checks allowed for Loop "
-        "Distribution for loop marked with #pragma loop distribute(enable)"));
+    cl::desc("The maximum number of SCEV checks allowed for Loop "
+             "Distribution for loop marked with #pragma clang loop "
+             "distribute(enable)"));
 
 static cl::opt<bool> EnableLoopDistribute(
     "enable-loop-distribute", cl::Hidden,

llvm/test/Analysis/LoopAccessAnalysis/pointer-phis.ll

@@ -202,7 +202,7 @@ exit:                                             ; preds = %loop.latch
 define i32 @store_with_pointer_phi_incoming_phi(ptr %A, ptr %B, ptr %C, i1 %c.0, i1 %c.1) {
 ; CHECK-LABEL: 'store_with_pointer_phi_incoming_phi'
 ; CHECK-NEXT:  loop.header:
-; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT:    Unknown data dependence.
 ; CHECK-NEXT:    Dependences:
 ; CHECK-NEXT:      Unknown:
@@ -279,7 +279,7 @@ exit:                                             ; preds = %loop.latch
 define i32 @store_with_pointer_phi_incoming_phi_irreducible_cycle(ptr %A, ptr %B, ptr %C, i1 %c.0, i1 %c.1) {
 ; CHECK-LABEL: 'store_with_pointer_phi_incoming_phi_irreducible_cycle'
 ; CHECK-NEXT:  loop.header:
-; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT:    Unknown data dependence.
 ; CHECK-NEXT:    Dependences:
 ; CHECK-NEXT:      Unknown:
@@ -417,7 +417,7 @@ exit:                                             ; preds = %loop.latch
 define void @phi_load_store_memdep_check(i1 %c, ptr %A, ptr %B, ptr %C) {
 ; CHECK-LABEL: Loop access info in function 'phi_load_store_memdep_check':
 ; CHECK-NEXT:   for.body:
-; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK-NEXT:    Report: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT:    Unknown data dependence.
 ; CHECK-NEXT:    Dependences:
 ; CHECK-NEXT:      Unknown:

llvm/test/Transforms/LoopVectorize/diag-with-hotness-info-2.ll

@@ -21,11 +21,11 @@
 ;  19	  }
 ;  20	}
 
-; CHECK: remark: /tmp/s.c:3:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: /tmp/s.c:3:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT: Backward loop carried data dependence. Memory location is the same as accessed at /tmp/s.c:3:16 (hotness: 300)
-; CHECK: remark: /tmp/s.c:10:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: /tmp/s.c:10:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT: Backward loop carried data dependence. Memory location is the same as accessed at /tmp/s.c:10:16 (hotness: 5000)
-; CHECK: remark: /tmp/s.c:17:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: /tmp/s.c:17:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT: Backward loop carried data dependence. Memory location is the same as accessed at /tmp/s.c:17:16{{$}}
 
 ; ModuleID = '/tmp/s.c'

llvm/test/Transforms/LoopVectorize/memory-dep-remarks.ll

@@ -149,7 +149,7 @@ for.body:                                         ; preds = %entry, %for.body
 ;   }
 ; }
 
-; CHECK: remark: source.c:48:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: source.c:48:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT: Backward loop carried data dependence. Memory location is the same as accessed at source.c:47:5
 
 define void @test_backward_dep(i64 %n, ptr nocapture %A) {
@@ -194,7 +194,7 @@ for.body:                                         ; preds = %for.body.preheader,
 ;   }
 ; }
 
-; CHECK: remark: source.c:61:12: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: source.c:61:12: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK-NEXT: Forward loop carried data dependence that prevents store-to-load forwarding. Memory location is the same as accessed at source.c:60:5
 
 define void @test_forwardButPreventsForwarding_dep(i64 %n, ptr nocapture %A, ptr nocapture %B) !dbg !166 {
@@ -232,7 +232,7 @@ for.body:                                         ; preds = %entry, %for.body
 ;   }
 ; }
 
-; CHECK: remark: source.c:74:5: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: source.c:74:5: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK: Backward loop carried data dependence that prevents store-to-load forwarding. Memory location is the same as accessed at source.c:74:21
 
 define void @test_backwardVectorizableButPreventsForwarding(i64 %n, ptr nocapture %A) !dbg !189 {
@@ -268,7 +268,7 @@ for.body:                                         ; preds = %entry, %for.body
 ;   }
 ; }
 
-; CHECK: remark: source.c:83:7: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: source.c:83:7: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ; CHECK: Unknown data dependence. Memory location is the same as accessed at source.c:82:7
 
 define void @test_unknown_dep(i64 %n, ptr nocapture %A) !dbg !214 {
@@ -315,7 +315,7 @@ for.body:                                         ; preds = %entry, %for.body
 ; YAML-NEXT: Function:        test_backward_dep
 ; YAML-NEXT: Args:
 ; YAML-NEXT:   - String:          'loop not vectorized: '
-; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
+; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
 ; YAML-NEXT:   - String:          "\nBackward loop carried data dependence."
 ; YAML-NEXT:   - String:          ' Memory location is the same as accessed at '
 ; YAML-NEXT:   - Location:        'source.c:47:5'
@@ -335,7 +335,7 @@ for.body:                                         ; preds = %entry, %for.body
 ; YAML-NEXT: Function:        test_forwardButPreventsForwarding_dep
 ; YAML-NEXT: Args:
 ; YAML-NEXT:   - String:          'loop not vectorized: '
-; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
+; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
 ; YAML-NEXT:   - String:          "\nForward loop carried data dependence that prevents store-to-load forwarding."
 ; YAML-NEXT:   - String:          ' Memory location is the same as accessed at '
 ; YAML-NEXT:   - Location:        'source.c:60:5'
@@ -355,7 +355,7 @@ for.body:                                         ; preds = %entry, %for.body
 ; YAML-NEXT: Function:        test_backwardVectorizableButPreventsForwarding
 ; YAML-NEXT: Args:
 ; YAML-NEXT:   - String:          'loop not vectorized: '
-; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
+; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
 ; YAML-NEXT:   - String:          "\nBackward loop carried data dependence that prevents store-to-load forwarding."
 ; YAML-NEXT:   - String:          ' Memory location is the same as accessed at '
 ; YAML-NEXT:   - Location:        'source.c:74:21'
@@ -375,7 +375,7 @@ for.body:                                         ; preds = %entry, %for.body
 ; YAML-NEXT: Function:        test_unknown_dep
 ; YAML-NEXT: Args:
 ; YAML-NEXT:   - String:          'loop not vectorized: '
-; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
+; YAML-NEXT:   - String:          'unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop'
 ; YAML-NEXT:   - String:          "\nUnknown data dependence."
 ; YAML-NEXT:   - String:          ' Memory location is the same as accessed at '
 ; YAML-NEXT:   - Location:        'source.c:82:7'

llvm/test/Transforms/LoopVectorize/unsafe-dep-remark.ll

@@ -11,7 +11,7 @@ target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 ;     5	  }
 ;     6	}
 
-; CHECK: remark: /tmp/kk.c:3:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK: remark: /tmp/kk.c:3:14: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 
 define void @success(ptr nocapture %A, ptr nocapture readonly %B, ptr nocapture %C, ptr nocapture readonly %D, ptr nocapture readonly %E, i32 %N) !dbg !6 {
 entry: